Make this test emit llvm IR rather than assembly.

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@209255 91177308-0d34-0410-b5e6-96231b3b80d8
libclang: Give each VirtualFileOverlay unit test its own name

git-svn-id: http://llvm.org/svn/llvm-project/cfe/trunk@209257 91177308-0d34-0410-b5e6-96231b3b80d8