Just forgot to include this in CL 12843043.
Also consolidates the code dealing with test environment.

Update #6122

R=alex.brainman
CC=golang-dev
https://golang.org/cl/13184043

R=golang-dev, dave, bradfitz, adg
CC=golang-dev
https://golang.org/cl/13249043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13232043

RFC 6265 allows a leading dot in a cookie domain attribute
but is clear (see section 4.1.1) that a Set-Cookie header
should be sent without these dots.

R=bradfitz
CC=golang-dev
https://golang.org/cl/13111043

With my apologies.

R=golang-dev, alex.brainman
CC=golang-dev
https://golang.org/cl/12984045

NetBSD 6 kernel and beyond require 64-bit aligned access to routing
facilities.

Fixes #6226.

R=golang-dev, bsiegert, bradfitz
CC=golang-dev
https://golang.org/cl/13170043

== isn't defined on slices, so don't use it in docs.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/12983045

OS X in particular deletes tmp files (but not directories)
pretty reliably.

Ask hg whether the go.tools directory in tmp is good before
using it.

Fixes issue Rob and others were reporting, which I just hit
myself now.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/13084049

This was breaking people setting GOARCH=386 before running
all.bash on amd64 machines.

cmd/go puts different architecture binaries where "go tool"
can't find them.

R=golang-dev, r, khr
CC=golang-dev
https://golang.org/cl/13139044

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/12917050

Current for Plan 9 is implemented with /dev/user for
Uid/Gid/Username/Name, and $home environment variable for
HomeDir.

Implementing Lookup/LookupId is not done, which would
require parsing /adm/users. It is unclear of how much benefit
this would be.

R=golang-dev
CC=bradfitz, golang-dev, r
https://golang.org/cl/13203043

Also use clone(2) syscall instead of fork().

Fixes #6214.

R=golang-dev, bradfitz, dave
CC=golang-dev
https://golang.org/cl/13159044

the use of the flag, especially for objects which actually do have
pointers but we don't want the GC to scan them.

R=golang-dev, cshapiro
CC=golang-dev
https://golang.org/cl/13181045

slice type to an array type, the haspointer-ness may change.
Before this change, we'd sometimes get types like [1]int marked
as having pointers.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13189044

Update #5780

R=golang-dev, cshapiro, dave, bradfitz
CC=golang-dev
https://golang.org/cl/12869049

Update #6214

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13160043

Enable remaining packages (crypto, mime, path, time) to build on dragonfly.

R=bradfitz
CC=golang-dev
https://golang.org/cl/13190043

Make the net package build and work on dragonfly.

R=bradfitz
CC=golang-dev
https://golang.org/cl/13173044

Make the os package build and work on dragonfly.

R=bradfitz
CC=golang-dev
https://golang.org/cl/13183044

Add generated z-files for dragonfly/amd64.

R=bradfitz
CC=golang-dev
https://golang.org/cl/13056045

Add syscall support for dragonfly/amd64.

Also add support for generating syscall z* files for dragonfly.

R=bradfitz
CC=golang-dev
https://golang.org/cl/13188043

Go runtime support for dragonfly/amd64, largely based of the existing
FreeBSD runtime (with some clues from the varialus/godfly work).

R=bradfitz
CC=golang-dev
https://golang.org/cl/13088044

Fixes #6227

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13183043

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/13189043

Add dragonflydynld to 5l and 8l so that they compile again.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12739048

Add dragonfly/amd64 support to the Go compiler, bootstrap and GOOS list.

R=devon.odell, bradfitz
CC=golang-dev
https://golang.org/cl/12796050

Also avoids platform-dependent datagram truncation in raw IP tests.
At least it's different between Windows and others.

Fixes #6122.

R=alex.brainman
CC=golang-dev
https://golang.org/cl/12843043

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13141045

This is an attempt to make our slow
windows-386 builder more reliable.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/12798045

Also makes variable names a bit cleaner.

R=golang-dev, dave, r
CC=golang-dev
https://golang.org/cl/12808047

Update #5344

R=alex.brainman
CC=golang-dev
https://golang.org/cl/12966046

R=golang-dev, adg
CC=golang-dev, mikioh.mikioh
https://golang.org/cl/12848047

This CL adds minimal information for supporting platforms that don't
have a complete list of internet protocol numbers.

Fixes #5344.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12898045

The net package consists of thin three layers like the follwoing;

- Exposed API, that contains net.Dial, net.DialUDP, net.DialUnix
- Socket and network file descriptor, that contains net.netFD and
  its methods, helper functions such as dialUDP, dialUnix
- Network pollster, that contains net.pollDesc and its methods

This CL removes redundant argument check which is already done by
API layer.

R=golang-dev, dave, bradfitz
CC=golang-dev
https://golang.org/cl/13092043

Fixes #5630.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/12884046

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/13105047

GC acquires worldsema, which is a goroutine-level semaphore
which parks goroutines. g0 can not be parked.
Fixes #6193.

R=khr, khr
CC=golang-dev
https://golang.org/cl/12880045

Update the original change but do not read interface types in
the arguments area.  Once the arguments area is zeroed as the
locals area is we can safely read interface type values there
too.

««« original CL description
undo CL 12785045 / 71ce80dc4195

This has broken the 32-bit builds.

««« original CL description
cmd/gc, runtime: use type information to scan interface values

R=golang-dev, rsc, dvyukov
CC=golang-dev
https://golang.org/cl/12785045
»»»

R=khr, golang-dev, khr
CC=golang-dev
https://golang.org/cl/13010045
»»»

R=khr, khr
CC=golang-dev
https://golang.org/cl/13073045

This slightly improves performance when a lot of timers are present

$ misc/benchcmp ../old_timers_m.txt ../new_timers_m.txt
benchmark                           old ns/op    new ns/op    delta
BenchmarkAfterFunc                       6884         6605   -4.05%
BenchmarkAfterFunc-2                     4473         4144   -7.36%
BenchmarkAfterFunc-3                     8601         6185  -28.09%
BenchmarkAfterFunc-4                     9378         8773   -6.45%
BenchmarkAfter                           7237         7278   +0.57%
BenchmarkAfter-2                         4638         3923  -15.42%
BenchmarkAfter-3                         8751         6239  -28.71%
BenchmarkAfter-4                         9223         8737   -5.27%
BenchmarkStop                             603          496  -17.74%
BenchmarkStop-2                           795          577  -27.42%
BenchmarkStop-3                           982          680  -30.75%
BenchmarkStop-4                          1164          739  -36.51%
BenchmarkSimultaneousAfterFunc            657          593   -9.74%
BenchmarkSimultaneousAfterFunc-2          816          757   -7.23%
BenchmarkSimultaneousAfterFunc-3          844          830   -1.66%
BenchmarkSimultaneousAfterFunc-4          785          771   -1.78%
BenchmarkStartStop                        238          239   +0.42%
BenchmarkStartStop-2                      249          234   -6.02%
BenchmarkStartStop-3                      271          268   -1.11%
BenchmarkStartStop-4                      293          295   +0.68%

R=golang-dev, dvyukov, bradfitz, r
CC=golang-dev
https://golang.org/cl/13094043

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/12780045