Pass PIC/PIE options to gcc when asking for defines.

These influence the __PIC__ and __PIE__ macros.

Change-Id: I7938a897584f49b6e1c4d66c6e69ec7adccf2ad6
Reviewed-by: Daniel Teske <daniel.teske@digia.com>
Clang: do not pass the CXTranslationUnit_Incomplete option for parsing.

This flag is meant to be used when generating pre-compiled headers.

Change-Id: I4758f36c5774e7da8c3b6cc401ea4245761d2278
Reviewed-by: Nikolai Kosjar <nikolai.kosjar@digia.com>