Fix compiler warnings

[Marek Polacek]

On Wed, May 06, 2015 at 04:58:03PM +0200, Jakub Jelinek wrote:
> Also, it would be nice to figure why gcc doesn't warn (for both meaningful
> changes, in the first snippet I believe gcc just determines the static
> function is noreturn and that is why it correctly doesn't warn).
> I thought Marek has added patches for the !x == Y case recently, so it would
> be nice to find out why we don't warn in that case.

Yes, I'd expect a warning to trigger on that.
 
> Similarly for the bool case, does clang warn on +/++ operation on bool (which
> is well defined, supposedly it should be some style warning?), or something
> else?

clang++ warns for
  bool b = false;
  b++;
but not for
  bool b = false;
  b += 2;

	Marek