Makefile: strip `wc` results

Change-Id: Ib41230d7c3333ce27c864fe5abd2cb0b0d7ad5ca
Makefile: use toolchain cpp for reprocessing

Mac OS X's clang system toolchain doesn't like the config for some reason

Change-Id: I399928cda1c7afa17cf0121d658824d67cee899c