x86_64: Don't mark __exitcall as __cold
gcc currently doesn't support attributes on types, so we can't use it
function pointers. This avoids some warnings on a gcc 4.3 build.
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>