perf tools, Alpha: Add Alpha support to perf.h

For the perf tool the patch implements an Alpha specific section
in the perf.h header file.

Signed-off-by: Michael Cree <mcree@orcon.net.nz>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1256545926-6972-1-git-send-email-mcree@orcon.net.nz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>