fixes latent bugs in go and defer

R=r
OCL=23613
CL=23613

R=r
DELTA=43  (29 added, 5 deleted, 9 changed)
OCL=23608
CL=23611

R=r
OCL=23602
CL=23602

R=r
OCL=23592
CL=23592

R=r
DELTA=30  (26 added, 0 deleted, 4 changed)
OCL=23533
CL=23569

R=rsc
DELTA=18  (18 added, 0 deleted, 0 changed)
OCL=23544
CL=23547

R=r
OCL=23542
CL=23542

R=r,gri
DELTA=472  (423 added, 2 deleted, 47 changed)
OCL=23522
CL=23541

R=ken
OCL=23534
CL=23534

R=ken
OCL=23532
CL=23532

R=ken
OCL=23528
CL=23528

R=ken
OCL=23519
CL=23521

R=ken
OCL=23520
CL=23520

R=rsc
DELTA=210  (118 added, 60 deleted, 32 changed)
OCL=23508
CL=23518

more caching, better hash functions, proper locking.
fixed a bug in interface comparison too.

R=ken
DELTA=177  (124 added, 10 deleted, 43 changed)
OCL=23491
CL=23493

added another channel test

R=r
OCL=23488
CL=23488

R=r
DELTA=49  (0 added, 0 deleted, 49 changed)
OCL=23480
CL=23487

descriptor.  Use it in the PollServer code.

6g currently accepts this code without this change, but it
should not.  Test case for the bug is bug133.go.

R=rsc
DELTA=10  (0 added, 0 deleted, 10 changed)
OCL=23451
CL=23486

when it should not be.  I couldn't get this any simpler; the
error seems to have to do with the order of the imports in
bug2.go.

R=rsc
DELTA=26  (26 added, 0 deleted, 0 changed)
OCL=23450
CL=23482

can be compared/hashed.

R=r
DELTA=351  (201 added, 80 deleted, 70 changed)
OCL=23423
CL=23481

- clarified comparisons of interfaces, slices, maps, channels
- removed respective TODO's

R=r
DELTA=76  (42 added, 16 deleted, 18 changed)
OCL=23132
CL=23479

R=rsc
DELTA=205  (205 added, 0 deleted, 0 changed)
OCL=23448
CL=23478

buganizer 1589219
channel is returning same values multiple times

R=r
OCL=23447
CL=23447

R=ken
OCL=23422
CL=23422

R=ken
OCL=23419
CL=23419

the two still share an interface and Kind; that's probably ok but might be worth revisiting.

R=rsc
DELTA=74  (1 added, 8 deleted, 65 changed)
OCL=23416
CL=23418

R=r
OCL=23403
CL=23403

for simplicity of user's code, optional arrays of bytes also don't have a pointer.
requires adding a "Set()" method to arrays in reflect.
still to do: protocol compilers, google/net/rpc.

R=rsc
DELTA=227  (36 added, 95 deleted, 96 changed)
OCL=23387
CL=23389

- fine-tuning of ast
- more accurate block pos info (improved printing in some cases)
- collecting local variables and fields
- more work on type checking
- lots of minor tweaks

R=r
OCL=23375
CL=23375

TBR=r
OCL=23335
CL=23335

though they still build in src/runtime.

use cgo instead of hand-written wrappers.

R=r
DELTA=740  (289 added, 300 deleted, 151 changed)
OCL=23326
CL=23331

use $GC in all_test.go for portability.

R=r
DELTA=19  (12 added, 0 deleted, 7 changed)
OCL=23305
CL=23325

- slightly simplified a couple of productions (CommClause, SwitchClause)
  by reordering

R=r
DELTA=5  (0 added, 0 deleted, 5 changed)
OCL=23304
CL=23323

before their compilation.

R=r
OCL=23300
CL=23300

R=rsc
DELTA=16  (12 added, 0 deleted, 4 changed)
OCL=23242
CL=23242

once we close this

R=r
OCL=23239
CL=23239

implement hiding lowercase methods m in
signatures by adding in a hash of the package name
to the type hash code.

remove remaining checks for internally-generated _ names:
they are all gone.

R=ken
OCL=23236
CL=23238

cuts simple test binary by 7%.
would be more except for reflection.

R=r
DELTA=126  (117 added, 4 deleted, 5 changed)
OCL=23163
CL=23237

R=rsc
DELTA=16  (16 added, 0 deleted, 0 changed)
OCL=23224
CL=23229

reference to a type which should not be visible.  The test
currently fails with 6g.

R=rsc
DELTA=7  (4 added, 0 deleted, 3 changed)
OCL=23222
CL=23225