runtime: test distribution of interface hashes.

LGTM=dvyukov
R=dvyukov, khr
CC=golang-codereviews
https://codereview.appspot.com/121030043
cmd/go: pass --build-id=none when generating a cgo .o

Some systems, like Ubuntu, pass --build-id when linking.  The
effect is to put a note in the output file.  This is not
useful when generating an object file with the -r option, as
it eventually causes multiple build ID notes in the final
executable, all but one of which are for tiny portions of the
file and are therefore useless.

Disable that by passing an explicit --build-id=none when
linking with -r on systems that might do this.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/119460043
go/parser: don't do method receiver checks at parse-time

The ast and printer don't care, and go/types can provide
a better error message.

This change requires an update to the tests for go/types
(go.tools repo). CL forthcoming.

Fixes issue 8493.

LGTM=adonovan
R=rsc, adonovan
CC=golang-codereviews
https://codereview.appspot.com/123010044
runtime: fix nacl/amd64p32 build
C compiler does not support unnamed fields.

LGTM=bradfitz
R=golang-codereviews, bradfitz
CC=golang-codereviews
https://codereview.appspot.com/124870043