And also enable it by default to be consistent with e.g. modernize-use-using.
This helps e.g. when running this check on client code where the macro is
provided by the system, so there is no easy way to modify it.
Reviewed By: JonasToth
Differential Revision: https://reviews.llvm.org/D53454
llvm-svn: 344871
Miklos Vajna