doc/go1.4.html: half of the small library changes

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://codereview.appspot.com/165090043
runtime: update comment for Callers

Attempt to clear up confusion about how to turn
the PCs reported by Callers into the file and line
number people actually want.

Fixes issue 7690.

LGTM=r, chris.cs.guy
R=r, chris.cs.guy
CC=golang-codereviews
https://codereview.appspot.com/163550043
runtime: fix line number in first stack frame in printed stack trace

Originally traceback was only used for printing the stack
when an unexpected signal came in. In that case, the
initial PC is taken from the signal and should be used
unaltered. For the callers, the PC is the return address,
which might be on the line after the call; we subtract 1
to get to the CALL instruction.

Traceback is now used for a variety of things, and for
almost all of those the initial PC is a return address,
whether from getcallerpc, or gp->sched.pc, or gp->syscallpc.
In those cases, we need to subtract 1 from this initial PC,
but the traceback code had a hard rule "never subtract 1
from the initial PC", left over from the signal handling days.

Change gentraceback to take a flag that specifies whether
we are tracing a trap.

Change traceback to default to "starting with a return PC",
which is the overwhelmingly common case.

Add tracebacktrap, like traceback but starting with a trap PC.

Use tracebacktrap in signal handlers.

Fixes issue 7690.

LGTM=iant, r
R=r, iant
CC=golang-codereviews
https://codereview.appspot.com/167810044
doc/go1.4.html: gccgo status

LGTM=iant, cmang
R=cmang, iant, rsc
CC=golang-codereviews
https://codereview.appspot.com/169760043
cmd/objdump: use cmd/internal/objfile

This removes a bunch of ugly duplicate code.
The end goal is to factor the disassembly code
into cmd/internal/objfile too, so that pprof can use it,
but one step at a time.

LGTM=r, iant
R=r, alex.brainman, iant
CC=golang-codereviews
https://codereview.appspot.com/149400043
doc/go1.4.html: final library changes
First draft now complete.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews
https://codereview.appspot.com/170750043
runtime: make TestCgoExternalThreadPanic run on windows

LGTM=rsc
R=golang-codereviews, bradfitz, rsc
CC=golang-codereviews
https://codereview.appspot.com/163540043
runtime: change top-most return PC from goexit to goexit+PCQuantum

If you get a stack of PCs from Callers, it would be expected
that every PC is immediately after a call instruction, so to find
the line of the call, you look up the line for PC-1.
CL 163550043 now explicitly documents that.

The most common exception to this is the top-most return PC
on the stack, which is the entry address of the runtime.goexit
function. Subtracting 1 from that PC will end up in a different
function entirely.

To remove this special case, make the top-most return PC
goexit+PCQuantum and then implement goexit in assembly
so that the first instruction can be skipped.

Fixes issue 7690.

LGTM=r
R=r
CC=golang-codereviews
https://codereview.appspot.com/170720043
cmd/objdump: disable test failing on arm5

TBR=adg
CC=golang-codereviews
https://codereview.appspot.com/167890043
tag go1.4beta1

TBR=rsc
R=r, rsc
CC=golang-codereviews
https://codereview.appspot.com/164240043
doc/go1.4.html: fix typo

LGTM=adg
R=r, adg
CC=golang-codereviews
https://codereview.appspot.com/165890043
doc/go1.4.html: tweak http.Transport.DialTLS wording

It doesn't simplify, because it wasn't even possible before.

LGTM=r
R=r
CC=golang-codereviews
https://codereview.appspot.com/164250043
[dev.power64] runtime: match argument/return type signedness in power64x assembly

Previously, the power64x runtime assembly was sloppy about
using sign-extending versus zero-extending moves of arguments
and return values.  I think all of the cases that actually
mattered have been fixed in recent CLs; this CL fixes up the
few remaining mismatches.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://codereview.appspot.com/162480043
[dev.power64] runtime: test CAS on large unsigned 32-bit numbers

This adds a test to runtime?check to ensure CAS of large
unsigned 32-bit numbers does not accidentally sign-extend its
arguments.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/162490044
[dev.power64] runtime: fix out-of-date comment in panic

LGTM=bradfitz
R=rsc, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/162500043
cmd/cgo: avoid worklist nondeterminism.

+ Regression test.

Fixes issue 9026.

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/162490043
misc/cgo/test: fix bad C test code that fails on some configurations

LGTM=rsc
R=rsc
CC=golang-codereviews
https://codereview.appspot.com/169800043
[dev.power64] runtime: make asm_power64x.s go vet-clean

No real problems found.  Just lots of argument names that
didn't quite match up.

LGTM=rsc
R=rsc, dave
CC=golang-codereviews
https://codereview.appspot.com/169790043
A+C: add Jed Denlea (Fastly corporate CLA)

LGTM=iant
R=golang-codereviews, iant
CC=adg, golang-codereviews
https://codereview.appspot.com/165170043
A+C: Nathan P Finch (individual CLA)

TBR=iant
R=iant
CC=golang-codereviews
https://codereview.appspot.com/155560045