clang -cc1 skips the driver so it never made sense to include these with the
Driver tests.
Basic type tests and flag tests generally both go in Frontend.
Now that the final -cc1 tests have been moved out of test/Driver, add a
local substitution to enforce and detect future mistakes.
These miscategorized tests were probably the source of confusion in r194817.
llvm-svn: 194919
Alp Toker