r224012 - Emit warning if define or undef reserved identifier or keyword.

[Joerg Sonnenberger]

On Mon, Dec 15, 2014 at 09:39:37AM -0800, Nico Weber wrote:
> You can look at the warnings this produces for Chromium in  a clang-cl
> build here:
> http://build.chromium.org/p/chromium.fyi/builders/CrWinClang/builds/832/steps/compile/logs/stdio
> (search for "warning(clang)").

Right, this is similiar to the set I see. The only strange one is
	#define inline _inline
do we support the _inline spelling in MS compat mode? If yes, I think it
should be conditionally accepted in that mode, otherwise not.

Joerg