perf bench: Modify builtin-bench.c for processing common options

This patch modifies builtin-bench.c for processing common
options. The first option added is "--format".
Users of perf bench will be able to specify output style by
--format.

Usage example:

 % ./perf bench sched messaging		# with no style specify
 (20 sender and receiver processes per group)
 (10 groups == 400 processes run)

         Total time:1.431 sec

 % ./perf bench --format=simple sched messaging # specified
 simple 1.431

Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1257808802-9420-3-git-send-email-mitake@dcl.info.waseda.ac.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>