[llgo] cmd/gllgo: handle/ignore more flags

Summary:
This diff is to support Debian packaging,
which sets various hardening-rleated flags
in CFLAGS. They don't make sense for Go,
so we just ignore them.

Reviewers: pcc

Subscribers: llvm-commits, axw

Differential Revision: http://reviews.llvm.org/D11288

llvm-svn: 242513
GitOrigin-RevId: 7a94f98beaf11daf0046e02e34d07c9970ff2b28
1 file changed