perf tools: Don't use code surrounded by __KERNEL__

We need to refactor code to be explicitely shared by the kernel and at
least the tools/ userspace programs, so, till we do that, copy the bare
minimum bitmap/bitops code needed by tools/perf.

Reported-by: "H. Peter Anvin" <hpa@zytor.com>
Cc: Frédéric Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>