As for the analyzer, this makes us independent of the default triple and will
most likely reduce the maintenance - e.g. the target implies certain internal
command line arguments, we will profit from added ones.

This fixes parsing of mingw headers with the clang code model.

Change-Id: I722b981125a80fac5f62a7af40a83ecdd7bbf811
Reviewed-by: Christian Kandeler <christian.kandeler@theqtcompany.com>