This CL makes it possible to run make.bash with
GOOS and GOARCH set to something other than
the native host GOOS and GOARCH.

As part of the CL, the tool directory moves from bin/tool/
to pkg/tool/goos_goarch where goos and goarch are
the values for the host system (running the build), not
the target.  pkg/ is not technically appropriate, but C objects
are there now tool (pkg/obj/) so this puts all the generated
binaries in one place (rm -rf $GOROOT/pkg cleans everything).
Including goos_goarch in the name allows different systems
to share a single $GOROOT on a shared file system.

Fixes #2920.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5645093

Generates an infinite stream (at least >1GB) of:

=== RUN TestTransportPersistConnLeak
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files
2012/02/13 22:20:19 http: Accept error: accept tcp 127.0.0.1:63972:
too many open files

R=bradfitz
CC=golang-dev
https://golang.org/cl/5661052

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5656048

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/5661051

Thanks to Sascha Matzke & Florian Weimer for diagnosing.

R=golang-dev, adg, bradfitz, kevlar
CC=golang-dev
https://golang.org/cl/5656046

Fixes #2941

R=golang-dev, rsc, adg
CC=golang-dev
https://golang.org/cl/5663046

R=gri, r
CC=golang-dev
https://golang.org/cl/5659048

        1, IMO, the fatal error "regfree: not a register" from 5g when
         compiling runtime/debug.go is due to gcc miscompile, it doesn't
         show up when compiled with -O0. But I still haven't thought of
         a way to fix this, should all ARM builds be built with -O0?
        2, fixed mksysnum_linux.pl, so zsysnum_linux_arm.go no longer
        needs to be hand-generated.
        3, regen all in pkg syscall for Linux/ARM on Debian 6.0
This CL is somewhat big, I'd like to split it if necessary.

R=rsc, dave
CC=golang-dev
https://golang.org/cl/5659044

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5657047

This was an implementation detail that snuck into the public interface.
*Writer.Create gives you an io.Writer, the *Writer itself was never
meant to be written to.

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/5654076

R=rsc
CC=golang-dev
https://golang.org/cl/5659045

I remembered that sendfile support was lacking a test.

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5652079

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5661047

Makes files like src/pkg/syscall/ztypes_linux_amd64.go easier to read.
(The copy that is checked in predates the //line output mode,
so this also preserves the status quo.)

R=golang-dev, iant, gri
CC=golang-dev
https://golang.org/cl/5655068

Fixes #2905.

R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/5645088

Also update build to be able to run mkbuiltin again.
The export form has changed a little, so builtin.c has
more diffs than unsafe.go.

In CL 5650069, I just edited the documentation, a rarely
successful method of change.

R=ken2
CC=golang-dev
https://golang.org/cl/5662043

Fixes #2998.

R=rsc
CC=golang-dev
https://golang.org/cl/5650078

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5654077

This was broken by https://golang.org/cl/5643066
which introduced lazy indentation printing.

Fixes #2990.

R=rsc
CC=golang-dev
https://golang.org/cl/5655067

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5649086

Drop reference to "machine type."  Specify that integer
overflow must be an error.  Drop requirement that exponent
must be 128 bits--that's a lot.  Clarify that floating point
expressions may be rounded, including intermediate values.

This is a reworking of https://golang.org/cl/5577068/ .

Fixes #2789.

R=r, rsc, r, gri, ken, ken, iant
CC=golang-dev, remyoudompheng
https://golang.org/cl/5655049

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5645099

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5650076

R=golang-dev, gri
CC=golang-dev
https://golang.org/cl/5650077

Restore package os/signal, with new API:
Notify replaces Incoming, allowing clients
to ask for certain signals only.  Also, signals
go to everyone who asks, not just one client.

This could plausibly move into package os now
that there are no magic side effects as a result
of the import.

Update runtime for new API: move common Unix
signal handling code into signal_unix.c.
(It's so easy to do this now that we don't have
to edit Makefiles!)

Tested on darwin,linux 386,amd64.

Fixes #1266.

R=r, dsymonds, bradfitz, iant, borman
CC=golang-dev
https://golang.org/cl/3749041

1) Remove the Reset() member in crypto/aes and crypto/des (and
   document the change).
2) Turn several empty error structures into vars. Any remaining error
   structures are either non-empty, or will probably become so in the
   future.
3) Implement SetWriteDeadline for TLS sockets. At the moment, the TLS
   status cannot be reused after a Write error, which is probably fine
   for most uses.
4) Make crypto/aes and crypto/des return a cipher.Block.

R=rsc, r
CC=golang-dev
https://golang.org/cl/5625045

one trie lookup per rune is needed. See forminfo.go for a description
of the new format.  Also included leading and trailing canonical
combining class in decomposition information.  This will often avoid
additional trie lookups.

R=r, r
CC=golang-dev
https://golang.org/cl/5616071

Thanks to Aaron Kemp for noticing.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/5645097

This is not the finished product,
but a good checkpoint from which to
proceed with further development.

R=golang-dev, dsymonds, r
CC=golang-dev
https://golang.org/cl/5571061

R=golang-dev, bradfitz, iant
CC=golang-dev
https://golang.org/cl/5639064

8g/cgen.c
        print format type mismatch

8l/asm.c
        resoff set and not used

gc/pgen.c
        misleading comparison INT > 0x80000000

gc/reflect.c
        dalgsym must be static to match forward declaration

gc/subr.c
        assumed_equal set and not used
        hashmem's second argument is not used

gc/walk.c
        duplicated (unreachable) code

R=rsc
CC=golang-dev
https://golang.org/cl/5651079

hammerCompareAndSwapPointer64 was only passing on
little-endian systems.  hammerCompareAndSwapPointer32 was
writing 8 bytes to a uint32 value on the heap.

R=rsc, dvyukov
CC=golang-dev
https://golang.org/cl/5654065

It did in fact break on the darwin/386 builder.
Will investigate later; reopened issue 2917.

R=golang-dev
CC=golang-dev
https://golang.org/cl/5654070

You could argue for changing all the others, but
Linux is outvoted, and the only time it matters
is when newfd==-1, in which case you can call Dup.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5650073

Fixes #2776.

There was a previous attempt at CL 5592043 but that
seems to have stalled.  This one is simpler, and more up to date
(correct handling of spdy, for example).

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5645091

The Date-Modified header truncates sub-second precision, so
use mtime < t+1s instead of mtime <= t to check for unmodified.

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/5655052

R=golang-dev, rsc
CC=golang-dev
https://golang.org/cl/5652078

Sorry, Mercurial failed me.

TBR=r, dsymonds
CC=golang-dev
https://golang.org/cl/5649080

Among other things, this avoids putting a testing.go:nnn:
prefix on every line of the stack trace.

R=golang-dev, r, dsymonds, r
CC=golang-dev
https://golang.org/cl/5651081

unsafe: delete Typeof, Reflect, Unreflect, New, NewArray

Part of issue 2955 and issue 2968.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/5650069