[toolchain] disable -Wtautological-compare for clang

[Roman Divacky]

On Mon, Oct 17, 2011 at 09:56:23AM -0700, Gerald Pfeifer wrote:
> On Mon, 17 Oct 2011, Alexander Best wrote:
> > any chance we could disable -Wtautological-compare for clang? i don't 
> > think comparing an unsigned int against < 0 is worth a warning. actually 
> > it's always nice to have such a seatbelt, in case somebody changes the 
> > type to int and forgets to introduce such a check.
> 
> I am on the fence on this one, for when I used the equivalent warning
> in GCC this did found a number of real issues that I then addressed for
> Wine (as an example).

I also think this warning is very useful. Even in the "< 0" case, just think of
the case when one meant "> 0" but typed the opposite.

roman