cmd/6c, cmd/8c: cut stack frames by about half

The routine that adds an automatic to the stack was
adding ptrsize-1 to the size before rounding up.
That addition would only make sense to turn a round down
into a round up. Before a round up, it just wastes a word.

The effect was that a 6c function with one local and
one two-word function call used (8+8)+(16+8) = 40 bytes
instead of 8+16 = 24 bytes.

The wasted space mostly didn't matter, but one place where
it does matter is when trying to stay within the 128-byte
total frame constraint for #pragma textflag 7 functions.

This only affects the C compilers, not the Go compilers.

5c already had correct code, which is now copied to 6c and 8c.

R=ken2
CC=golang-dev
https://codereview.appspot.com/7303099
cmd/6c: fix build

copy+paste error while cleaning up CL 7303099 before submit

R=ken2
CC=golang-dev
https://codereview.appspot.com/7308104
runtime: preparation for non-Go threads running Go code

* Handle p==nil in signalstack by setting SS_DISABLE flag.
* Make minit only allocate a signal g if there's not one already.

R=golang-dev, r
CC=golang-dev
https://codereview.appspot.com/7323072
go/types: Pkg *Package field for all objects

The field is nil for predeclared (universe)
objects and parameter/result variables.

R=adonovan
CC=golang-dev
https://codereview.appspot.com/7312093
go/types: Permit dereferencing of named pointer types.

R=golang-dev, gri
CC=golang-dev
https://codereview.appspot.com/7358044

Committer: Robert Griesemer <gri@golang.org>
exp/cookiejar: store cookies under TLD+1 on nil public suffix list

The current implementation would store all cookies received from
any .com domain under "com" in the entries map if a nil public
suffix list is used in constructing the Jar. This is inefficient.

This CL uses the TLD+1 of the domain if the public suffix list
is nil which has two advantages:
 - It uses the entries map efficiently.
 - It prevents a host foo.com to set cookies for bar.com.
   (It may set the cookie, but it won't be returned to bar.com.)
A domain like www.british-library.uk may still set a domain
cookie for .british-library.uk in this case.

The behavior for a non-nil public suffix list is unchanged, cookies
are stored under eTLD+1 in this case.

R=nigeltao
CC=golang-dev
https://codereview.appspot.com/7312105

Committer: Nigel Tao <nigeltao@golang.org>
src/run.rc: "go env -9" is not valid, the correct command is "go tool dist env -9".

R=minux.ma, bradfitz
CC=golang-dev
https://codereview.appspot.com/7307120

Committer: Shenghou Ma <minux.ma@gmail.com>
doc/gccgo_contribute: mention gofrontend-dev@googlegroups.com mailing list

R=iant
CC=golang-dev
https://codereview.appspot.com/7323064