C++: Cleanup preprocessor tests

Change-Id: Ia1b7dee24a3d7e20440dca5040cf9ffdaaf066e2
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>
C++: Consolidate with/without comments preprocessor tests

Change-Id: Ib08569d642da51f6d51bb0763fc95d5a5c13d28c
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>