Add a test case that would have caught the bug fixed in r126640.
Add a test case that would have caught the bug fixed in r126640.

I've only covered C++'s flags here, we should probably do something
similar for ObjC flags.

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@126641 91177308-0d34-0410-b5e6-96231b3b80d8

llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,apple/swift-clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,llvm-mirror/clang,apple/swift-clang,apple/swift-clang