cpumask: introduce new APIs

In linux-next there is a commit ("x86: Add performance variants of cpumask
operators") which, as part of the 4096 cpu support work adds some new APIs
for dealing with cpu masks.  Add trivial versions of these now so that
subsystems can update in a timely manner and avoid conflicts in linux-next
and the next merge window.

Cc: Mike Travis <travis@sgi.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>