The wildcard 'std' is defined in documentation to be all the packages
in the Go standard library. It has also historically matched commands
in the main repo, but as we implement core commands in Go, that
becomes problematic. We need a wildcard that means just the library,
and since 'std' is already documented to have that definition, make it so.

Add a new wildcard 'cmd' for the commands in the main repo ($GOROOT).
Commands that want both can say 'std cmd' (or 'cmd std') to get the
effect of the old 'std'.

Update make.bash etc to say both std and cmd most of the time.

Exception: in race.bash, do not install race-enabled versions of
the actual commands. This avoids trying to write binaries while
using them, but more importantly it avoids enabling the race
detector and its associated memory overhead for the already
memory-hungry compilers.

Change-Id: I26bb06cb13b636dfbe71a015ee0babeb270a0275
Reviewed-on: https://go-review.googlesource.com/5550
Run-TryBot: Russ Cox <rsc@golang.org>
Reviewed-by: Rob Pike <r@golang.org>