Introduce 3 new fixit options:

-fixit-recompile
	applies fixits and recompiles the result
-fixit-to-temporary
	applies fixits to temporary files
-fix-only-warnings">,
    applies fixits for warnings only, not errors

Combining "-fixit-recompile -fixit-to-temporary" allows testing the result of fixits
without touching the original sources.

llvm-svn: 149027