Don't measure wall time in map.go. Keep it portable
and only test NaN, but not time.

Move time tests to mapnan.go and only measure user CPU time,
not wall time. It builds on Darwin and Linux, the primary
platforms where people hack on the runtime & in particular
maps. The runtime is shared, though, so we don't need it to
run on all of the platforms.

Fixes flaky build failures like:
http://build.golang.org/log/ba67eceefdeaa1142cb6c990a62fa3ffd8fd73f8

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8479043

R=golang-dev, dvyukov, bradfitz
CC=golang-dev
https://golang.org/cl/8366044

Before, an empty TMPDIR would lead to:
cannot create <nil>/go.o: No such file or directory

R=golang-dev, iant, dave, bradfitz
CC=golang-dev
https://golang.org/cl/8355045

R=golang-dev, iant, dave
CC=golang-dev
https://golang.org/cl/8253045

The invariant is that there must be at least one running P or a thread polling network.
It was broken.
Fixes #5216.

R=golang-dev, bradfitz, r
CC=golang-dev
https://golang.org/cl/8459043

This makes it an unsafe.Pointer in Go so the garbage collector
will treat it as a pointer to untyped data, not a pointer to
bytes.

R=golang-dev, dvyukov
CC=golang-dev
https://golang.org/cl/8286045

Unions can break precise GC.
Update #5193.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8362046

Unions can break precise GC.
Update #5193.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8457043

Unions can break precise GC.
Update #5193.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8456043

Unions break precise GC.
Update #5193.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8368044

+untype it because it can point to different types
Update #5193.

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8454043

If for whatever reason seh points into Go heap region,
the dangling pointer will cause memory corruption during GC.
Update #5193.

R=golang-dev, alex.brainman, iant
CC=golang-dev
https://golang.org/cl/8402045

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/8437043

Fixes #5226.

R=golang-dev, minux.ma, iant
CC=golang-dev
https://golang.org/cl/8320044

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/8441045

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8429045

The offset of an embedded field s.X must be relative to s
and not to the implicit s.Field of which X is a direct field.
Moreover, no indirections may happen on the path.

Fixes #4909.

R=nigeltao, ality, daniel.morsing, iant, gri, r
CC=golang-dev
https://golang.org/cl/8287043

Makes finding the relevant information much easier.

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/8353045

These no longer allocate.

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/8340047

R=golang-dev, dvyukov, khr, cshapiro
CC=golang-dev
https://golang.org/cl/8392043

Expands the example when visiting a URL such as
http://golang.org/pkg/net/http/#example_Hijacker

Fixes #5212.

R=golang-dev, bradfitz, adg
CC=golang-dev
https://golang.org/cl/8378043

We've decided to leave logging to third-parties (there are too
many formats), which others have done.

And we can't change the behavior of the various response
fields at this point anyway. Plus I argue they're correct and
match their documention.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8391043

Motivated by a deletion in the wiki, which had a better
example.

R=golang-dev, r
CC=golang-dev
https://golang.org/cl/8288045

R=golang-dev, iant
CC=golang-dev
https://golang.org/cl/8379043

Fixed example program's output to match program's code.
Fixes #5204.

R=golang-dev, minux.ma
CC=golang-dev
https://golang.org/cl/8365043

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/8377043

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/8248044

Generated by addca.

R=gobot
CC=golang-dev
https://golang.org/cl/8357043

R=r, minux.ma, bradfitz
CC=golang-dev
https://golang.org/cl/8304043

R=r
CC=golang-dev
https://golang.org/cl/8301044

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/8343046

Also, don't build the tour when making the source distribution.

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/8354043

R=golang-dev, dave
CC=golang-dev
https://golang.org/cl/8342046

R=golang-dev, dsymonds
CC=golang-dev
https://golang.org/cl/8343045

The compilers used to generate only one 'm' symbol
to record the stack frame size for each function.

In cmd/nm, the 'm' and 'f' symbols are handled in
the same switch case with a special exception for
the symbol described above called ".frame".

Now that the compilers emit additional 'm' symbols
for precise garbage collection of the stack, the
current logic is incorrect. cmd/nm will attempt to
interpret these new 'm' symbols as 'f' symbols and
add them to the file name index table.

This fails with an out-of-memory condition when
zenter encounters an 'm' symbol with a very large
value (usually the .args symbol indicating a
variadic NOSPLIT function).

R=iant
CC=dave, gobot, golang-dev, rsc
https://golang.org/cl/7962045

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8350044

Fixes 5164.

R=golang-dev, iant, adg
CC=golang-dev
https://golang.org/cl/8119049

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8342044

R=golang-dev, adg
CC=golang-dev
https://golang.org/cl/8285044

R=golang-dev, bradfitz
CC=golang-dev
https://golang.org/cl/8351043