cmd/go: check for another GCC error message

GCC always recognizes the -fsplit-stack option, but then tests whether
it is supported by the selected target. If not, it reports
    cc1: error: ‘-fsplit-stack’ is not supported by this compiler configuration
Check for that error message when deciding whether a compiler option works.

Change-Id: I50e5df330ac3c0564e9f0f06d084abbe304b3b3b
Reviewed-on: https://go-review.googlesource.com/87137
Reviewed-by: Than McIntosh <thanm@google.com>
1 file changed