This adds a lit reproducer that verifies that no temporary
assembly files are left behind when using clang-tidy with a
target that does not support the internal assembler.
The fix is in Tooling (https://reviews.llvm.org/D45686), but
as we need to verify that no files are left behind, it is
probably easier and better to create a lit reproducer for a
specific tool here instead of creating a unit test.