resending some missed warning fixes

[Jamey Sharp]

These two patches weren't applied or reviewed. I don't know of a reason
they shouldn't be applied though.

- Suppress GCC warnings like "the address of `u1' will always evaluate
  as `true'".
- Don't cast double to int: use default conversions or explicitly round.


Guillem Jover reviewed this patch and gave suggestions, but I'm
resending it without changes. Details in that mail:

- Suppress certain GCC warnings in auto-generated code.


Two other patches that I'd proposed were controversial at best, and I'm
not resubmitting them at the moment:

- Replace miPointerCurrentScreen with miPointerGetScreen.
- Use PRId32/PRIx32 from inttypes.h for printf of CARD32 values.


If the first three get applied then I think all my xserver patches are
accounted for.

Jamey