Make thinlto clang test more robust against LLVM changes.
Make thinlto clang test more robust against LLVM changes.

We should just test the effect of the clang level option here, i.e.
that a summary is correctly emitted with -flto=thin

From: Mehdi Amini <mehdi.amini@apple.com>

git-svn-id: ffe668792ed300d6c2daa1f6eba2e0aa28d7ec6c@267321 91177308-0d34-0410-b5e6-96231b3b80d8

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