libgo/Makefile, libgo/go/os/stat_atimespec.go: fix typos

R=iant
CC=gofrontend-dev
https://codereview.appspot.com/7158043

Committer: Ian Lance Taylor <iant@golang.org>
all: prepend #__USER_LABEL_PREFIX__ to mangled Go symbols
For old-fashioned Darwin.

R=iant
CC=gofrontend-dev
https://codereview.appspot.com/7086062

Committer: Ian Lance Taylor <iant@golang.org>