Fix tests that weren't actually verifying anything.

Passing -verify to clang without -cc1 or -Xclang silently passes (with a
printed warning, but lit doesn't care about that). This change adds -cc1 or,
as is necessary in one case, -Xclang to fix this so that these tests are
actually verifying as intended.

I'd like to change the driver so this kind of mistake could not be made, but
I'm not entirely sure how. Further, since the driver only warns about unknown
flags in general, we could have similar bugs with a misspellings of arguments
that would be nice to find.

llvm-svn: 154776