Tweak gnu-flags.c test for z, where globals have 2-byte alignment by default


git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@188905 91177308-0d34-0410-b5e6-96231b3b80d8
Centralize the handling of -target-feature.

No functionality change other than changing the order of -target-feature
relative to other -cc1 command line arguments.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@188906 91177308-0d34-0410-b5e6-96231b3b80d8