cmd/ld: Put the textflag constants in a separate file.
We can then include this file in assembly to replace
cryptic constants like "7" with meaningful constants
like "(NOPROF|DUPOK|NOSPLIT)".

Converting just pkg/runtime/asm*.s for now.  Dropping NOPROF
and DUPOK from lots of places where they aren't needed.
More .s files to come in a subsequent changelist.

A nonzero number in the textflag field now means
"has not been converted yet".

R=golang-dev, daniel.morsing, rsc, khr
CC=golang-dev
https://codereview.appspot.com/12568043
test: fix return.go to not use fallthrough in a type switch

The gc compiler only gives an error about fallthrough in a
type switch if it has not given any errors in an earlier pass.
Remove all functions in this test that use fallthrough in a
type switch because they don't test anything useful and they
cause gccgo to give unexpected errors.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12614043
test: fix return.go to remove unused labels

The gc compiler only gives an error about an unused label if
it has not given any errors in an earlier pass.  Remove all
unused labels in this test because they don't test anything
useful and they cause gccgo to give unexpected errors.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12580044
test: add cases to return.go that gccgo got wrong

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12620043
net/http: Various fixes to Basic authentication

There were some issues with the code sometimes using base64.StdEncoding,
and sometimes base64.URLEncoding.
Encoding basic authentication is now always done by the same code.

Fixes issue 5970.

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12397043

Committer: Brad Fitzpatrick <bradfitz@golang.org>
runtime: convert .s textflags from numbers to symbolic constants.
Remove NOPROF/DUPOK from everything.

Edits done with a script, except pclinetest.asm which depended
on the DUPOK flag on main().

R=golang-dev, bradfitz
CC=golang-dev
https://codereview.appspot.com/12613044
cmd/cc, cmd/gc, runtime: emit bitmaps for scanning locals.

Previously, all word aligned locations in the local variables
area were scanned as conservative roots.  With this change, a
bitmap is generated describing the locations of pointer values
in local variables.

With this change the argument bitmap information has been
changed to only store information about arguments.  The locals
member, has been removed.  In its place, the bitmap data for
local variables is now used to store the size of locals.  If
the size is negative, the magnitude indicates the size of the
local variables area.

R=rsc
CC=golang-dev
https://codereview.appspot.com/12328044
runtime: do not run TestCgoSignalDeadlock on windows in short mode
The test takes up to 64 seconds on windows builders.
I've tried to reduce number of iterations in the test,
but it does not affect run time.
Fixes issue 6054.

R=golang-dev, alex.brainman
CC=golang-dev
https://codereview.appspot.com/12531043