Compiling an allyesconfig kernel straight with a gcc 4.0 snapshot gives
nearly 10k new warnings like:

warning: pointer targets in passing argument 5 of `cpuid' differ in signedness

Since the sheer number of these warnings was too much even for the most
determined kernel janitors (I actually asked ;-) and I don't think it's a
very serious issue to have these mismatches I submitted an new option to
gcc to disable it.  It was incorporated in gcc mainline now.

This patch makes the kernel compilation use it.  There are still quite a
lot of new warnings with 4.0 (mostly about uninitialized variables), but
the compile log looks much nicer nnow.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>