runtime: rename throwgo to gothrow

As pointed out by Elias Naur, the convention for Go runtime functions means this function should be named gothrow.

Discussion: https://codereview.appspot.com/115860045/#msg6

LGTM=dvyukov
R=golang-codereviews, dvyukov
CC=golang-codereviews
https://codereview.appspot.com/118120043
syscall: allow for mksyscall_windows.go to be used outside of syscall

Fixes issue 8398.

LGTM=chines
R=golang-codereviews, chines, josharian
CC=golang-codereviews
https://codereview.appspot.com/114140043
testing: add Coverage function

I've found this very useful for generating
good test case lists for -short mode for
the disassemblers.

Fixes issue 7959.

LGTM=r
R=r
CC=golang-codereviews
https://codereview.appspot.com/98150043
doc/go1.4.txt: windows can do symlinks now

R=golang-codereviews
CC=golang-codereviews
https://codereview.appspot.com/111560043
cmd/gc: mark auxiliary symbols as containing no pointers
They do not, but pretend that they do.
The immediate need is that it breaks the new GC because
these are weird symbols as if with pointers but not necessary
pointer aligned.

LGTM=rsc
R=golang-codereviews, dave, josharian, khr, rsc
CC=golang-codereviews, iant, khr, rlh
https://codereview.appspot.com/116060043
lib9: format %#04x, 0 as 0x0000 not 000000.

This matches Go's fmt.Printf instead of ANSI C's dumb rules.
It makes the -S output from C liblink match Go's liblink.

LGTM=minux
R=minux
CC=golang-codereviews
https://codereview.appspot.com/112600043
liblink: more precise literal word comparison on arm

There are fields in the Addr that do not matter for the
purpose of deciding that the same word is already
in the current literal pool. Copy only the fields that
do matter.

This came up when comparing against the Go version
because the way it is invoked doesn't copy a few fields
(like node) that are never directly used by liblink itself.

Also remove a stray print that is not well-defined in
the new liblink. (Cannot use %D outside of %P, because
%D needs the outer Prog*.)

LGTM=minux
R=minux
CC=golang-codereviews
https://codereview.appspot.com/119000043
runtime: fix unexpected return pc for runtime.newstackcall
With cl/112640043 TestCgoDeadlockCrash episodically print:
unexpected return pc for runtime.newstackcall
After adding debug output I see the following trace:

runtime: unexpected return pc for runtime.newstackcall called from 0xc208011b00
runtime.throw(0x414da86)
        src/pkg/runtime/panic.c:523 +0x77
runtime.gentraceback(0x40165fc, 0xba440c28, 0x0, 0xc208d15200, 0xc200000000, 0xc208ddfd20, 0x20, 0x0, 0x0, 0x300)
	src/pkg/runtime/traceback_x86.c:185 +0xca4
runtime.callers(0x1, 0xc208ddfd20, 0x20)
	src/pkg/runtime/traceback_x86.c:438 +0x98
mcommoninit(0xc208ddfc00)
	src/pkg/runtime/proc.c:369 +0x5c
runtime.allocm(0xc208052000)
	src/pkg/runtime/proc.c:686 +0xa6
newm(0x4017850, 0xc208052000)
	src/pkg/runtime/proc.c:933 +0x27
startm(0xc208052000, 0x100000001)
	src/pkg/runtime/proc.c:1011 +0xba
wakep()
	src/pkg/runtime/proc.c:1071 +0x57
resetspinning()
	src/pkg/runtime/proc.c:1297 +0xa1
schedule()
	src/pkg/runtime/proc.c:1366 +0x14b
runtime.gosched0(0xc20808e240)
	src/pkg/runtime/proc.c:1465 +0x5b
runtime.newstack()
	src/pkg/runtime/stack.c:891 +0x44d
runtime: unexpected return pc for runtime.newstackcall called from 0xc208011b00
runtime.newstackcall(0x4000cbd, 0x4000b80)
	src/pkg/runtime/asm_amd64.s:278 +0x6f

I suspect that it can happen on any stack split.
So don't unwind g0 stack.
Also, that comment is lying -- we can traceback w/o mcache,
CPU profiler does that.

LGTM=rsc
R=golang-codereviews
CC=golang-codereviews, khr, rsc
https://codereview.appspot.com/120040043
runtime: don't lock mheap on user goroutine
This is bad for 2 reasons:
1. if the code under lock ever grows stack,
it will deadlock as stack growing acquires mheap lock.
2. It currently deadlocks with SetCPUProfileRate:
scavenger locks mheap, receives prof signal and tries to lock prof lock;
meanwhile SetCPUProfileRate locks prof lock and tries to grow stack
(presumably in runtime.unlock->futexwakeup). Boom.
Let's assume that it
Fixes issue 8407.

LGTM=rsc
R=golang-codereviews, rsc
CC=golang-codereviews, khr
https://codereview.appspot.com/112640043
misc/pprof: support web profiles on windows/MinGW

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/117060043

Committer: Brad Fitzpatrick <bradfitz@golang.org>
net/http: don't ignore errors in Request.Write

LGTM=josharian, adg
R=golang-codereviews, josharian, adg
CC=golang-codereviews
https://codereview.appspot.com/119110043