consistent with OLROT. Delete unused OBAD, OLRC.

R=rsc, dave
CC=golang-dev
https://golang.org/cl/6489082

The old code was a depth first graph traversal that could, under the
right conditions, end up re-exploring the same subgraphs multiple
times, once for each way to arrive at that subgraph at a given depth.

The new code uses a breadth first search to make sure that it only
visits each reachable embedded struct once.

Also add fast path for the trivial case.

benchmark                old ns/op    new ns/op    delta
BenchmarkFieldByName1         1321          187  -85.84%
BenchmarkFieldByName2         6118         5186  -15.23%
BenchmarkFieldByName3      8218553        42112  -99.49%

R=gri, r
CC=golang-dev
https://golang.org/cl/6458090

R=nigeltao
CC=golang-dev
https://golang.org/cl/6499075

R=dsymonds
CC=golang-dev
https://golang.org/cl/6503070

R=rsc, daniel.morsing
CC=golang-dev
https://golang.org/cl/6495074

R=golang-dev, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6490076

All of them call `newFileFD' which must properly restore close-on-exec on
duplicated fds.

R=golang-dev, bradfitz, mikioh.mikioh
CC=golang-dev
https://golang.org/cl/6445081

Signal handlers are global resources but many language
environments (Go, C++ at Google, etc) assume they have sole
ownership of a particular handler.  Signal handlers in
mixed-language applications must therefore be robust against
unexpected delivery of certain signals, such as SIGPROF.

The default Go signal handler runtime·sigtramp assumes that it
will never be called on a non-Go thread, but this assumption
is violated by when linking in C++ code that spawns threads.
Specifically, the handler asserts the thread has an associated
"m" (Go scheduler).

This CL is a very simple workaround: discard SIGPROF delivered to non-Go threads.  runtime.badsignal(int32) now receives the signal number; if it returns without panicking (e.g. sig==SIGPROF) the signal is discarded.

I don't think there is any really satisfactory solution to the
problem of signal-based profiling in a mixed-language
application.  It's not only the issue of handler clobbering,
but also that a C++ SIGPROF handler called in a Go thread
can't unwind the Go stack (and vice versa).  The best we can
hope for is not crashing.

Note:
- I've ported this to all POSIX platforms, except ARM-linux which already ignores unexpected signals on m-less threads.
- I've avoided tail-calling runtime.badsignal because AFAICT the 6a/6l don't support it.
- I've avoided hoisting 'push sig' (common to both function calls) because it makes the code harder to read.
- Fixed an (apparently incorrect?) docstring.

R=iant, rsc, minux.ma
CC=golang-dev
https://golang.org/cl/6498057

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6489065

Fixes #3178.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/6506064

Fixes #3667.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/6492078

Added instructions for starting an http server
to the godoc header for this package.  With the old
instructions, the example "go tool pprof..." commands
wouldn't work unless you happen to be running an http
server on port 6060 in your application.

R=golang-dev, minux.ma, adg, giacomo.tartari
CC=golang-dev
https://golang.org/cl/6483049

Fixes #3945.

R=golang-dev, minux.ma
CC=golang-dev, vcc.163
https://golang.org/cl/6490056

It is enabled by mistake and should be part of CL 5847068 instead.

R=golang-dev
CC=golang-dev, minux.ma
https://golang.org/cl/6488073

R=golang-dev, dave, rsc
CC=golang-dev
https://golang.org/cl/6449127

        cgo[1-4].go, go1.go couldn't be tested now
(cgo[1-4].go can only be tested when cgo is enabled, go1.go
contain a list of filenames in the current directory)

R=golang-dev, alex.brainman, rsc
CC=golang-dev
https://golang.org/cl/6218048

Fixes #3853.

R=ken2
CC=golang-dev
https://golang.org/cl/6492071

The decorator hides the number of function arguments from Mercurial,
so Mercurial cannot give proper error messages about commands
invoked with the wrong number of arguments.

Left a 'dummy' hgcommand decorator in place as a way to document
what functions are hg commands, and just in case we need some other
kind of hack in the future.

R=adg, rsc
CC=golang-dev
https://golang.org/cl/6488059

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6492070

R=golang-dev, r, dave, rsc
CC=golang-dev
https://golang.org/cl/6492069

Accomplished by synchronizing the formatting of conversion errors between typecheck.c and subr.c

Fixes #3984.

R=golang-dev, remyoudompheng, rsc
CC=golang-dev
https://golang.org/cl/6500064

Fixes #3909.
Fixes #3910.

R=rsc, nigeltao
CC=golang-dev
https://golang.org/cl/6442114

There was mail on golang-nuts a few weeks ago
from someone who understood the message perfectly
and knew he had a cyclic dependency but assumed
that Go, like Python or Java, was supposed to handle it.

R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/6488069

The performance improvement applies to the case where
prec >= 0 and fmt is 'e' or 'g'.

Additional minor optimisations are included. A small
performance impact happens in some cases due to code
refactoring.

benchmark                              old ns/op    new ns/op    delta
BenchmarkAppendFloat64Fixed1                 623          235  -62.28%
BenchmarkAppendFloat64Fixed2                1050          272  -74.10%
BenchmarkAppendFloat64Fixed3                3723          243  -93.47%
BenchmarkAppendFloat64Fixed4               10285          274  -97.34%

BenchmarkAppendFloatDecimal                  190          206   +8.42%
BenchmarkAppendFloat                         387          377   -2.58%
BenchmarkAppendFloatExp                      397          339  -14.61%
BenchmarkAppendFloatNegExp                   377          336  -10.88%
BenchmarkAppendFloatBig                      546          482  -11.72%

BenchmarkAppendFloat32Integer                188          204   +8.51%
BenchmarkAppendFloat32ExactFraction          329          298   -9.42%
BenchmarkAppendFloat32Point                  400          372   -7.00%
BenchmarkAppendFloat32Exp                    369          306  -17.07%
BenchmarkAppendFloat32NegExp                 372          305  -18.01%

R=golang-dev, rsc
CC=golang-dev, remy
https://golang.org/cl/6462049

for both locale-specific exemplar characters and tailorings to
the collation table.
Some specifices:
- Moved stringSet to the beginning of the file and added some functionality
  to parse command line files.
- openReader now modifies the input URL for localFiles to guarantee that
  any http source listed in the generated file is indeed this source.
- Note that the implementation of the Tailoring API used by maketables.go
  is not yet checked in. So for now adding tailorings are simply no-ops.
- The generated file of exemplar characters will be used somewhere else.
  Here is a snippet of how the body of the generated file looks like:

type exemplarType int
const (
        exCharacters exemplarType = iota
        exContractions
        exPunctuation
        exAuxiliary
        exCurrency
        exIndex
        exN
)

var exemplarCharacters = map[string][exN]string{
        "af": [exN]string{
                0: "a á â b c d e é è ê ë f g h i î ï j k l m n o ô ö p q r s t u û v w x y z",
                3: "á à â ä ã æ ç é è ê ë í ì î ï ó ò ô ö ú ù û ü ý",
                4: "a b c d e f g h i j k l m n o p q r s t u v w x y z",
        },
        ...
}

R=r
CC=golang-dev
https://golang.org/cl/6501070

- Elements in the array are now sorted as a linked list.  This makes it easier to
  apply tailorings.
- Added code to sort entries by collation elements.
- Added logical reset points.  This is used for tailoring relative to certain
  properties, rather than characters.

NOTE: all code for type entry should now be in order.go.  To keep the diffs for
this CL reasonable, though, the existing code is left in builder.go.  I'll move
this in a separate CL.

R=r
CC=golang-dev
https://golang.org/cl/6493063

Fixes #3525.

PTRACE_SYSCALL behaves like PTRACE_CONT and can deliver
a signal to the process. Ideally PtraceSingleStep should
support the signal argument, but its interface is frozen
by Go1.

R=golang-dev, r, rsc
CC=golang-dev
https://golang.org/cl/6353051

TBR=r
CC=golang-dev
https://golang.org/cl/6497067

Parses a time header value into a time.Time according to rfc2616 sec 3.3.

R=golang-dev, dave, rsc, r
CC=bradfitz, golang-dev
https://golang.org/cl/6344046

R=rsc, n13m3y3r
CC=golang-dev
https://golang.org/cl/6330061

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6492067

R=iant, imkrasin, krasin, iant, minux.ma, rsc, nigeltao, r, fullung
CC=golang-dev
https://golang.org/cl/6454046

Fixes #3975.

R=rsc, lvd
CC=golang-dev, remy
https://golang.org/cl/6475061

A crash happens in the first request in a connection
if "params" field is missing because c.req.Params is Nil.

Fixes #3848.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/6446051

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/6497066

Reverts part of CL 6460082.

If a doc comment describes a type by explaining the
meaning of one instance of the type, a leading article
is fine and makes the text less awkward.

Compare:
// A dog is a kind of animal.
// Dog is a kind of animal.

R=golang-dev, dsymonds, dvyukov, r
CC=golang-dev
https://golang.org/cl/6494066

This set of changes extends the Plan 9 support
to include the AMD64 architecture and should
work on all versions of Plan 9.

R=golang-dev, rminnich, noah.evans, rsc, minux.ma, npe
CC=akskuma, golang-dev, jfflore, noah.evans
https://golang.org/cl/6479052

This fixes a spurious 'invalid recursive type' error, and stops the compiler from emitting errors on uses of the invalid type.

Fixes #3766.

R=golang-dev, dave, minux.ma, rsc
CC=golang-dev
https://golang.org/cl/6443100

The Handler method makes the ServeMux dispatch logic
available to wrappers that enforce additional constraints
on requests.

R=golang-dev, bradfitz, dsymonds
CC=golang-dev
https://golang.org/cl/6450165

In serve mux, if pattern contains a host name, pass only the path to
the redirect handler.

Add tests for serve mux redirections.

R=rsc
CC=bradfitz, gobot, golang-dev
https://golang.org/cl/6329045