perf report: Add --no-demangle option

It's sometimes useful to see undemangled raw symbol name for example
other tools using the perf output to do manipulation of binaries.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Suggested-by: William Cohen <wcohen@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: William Cohen <wcohen@redhat.com>
BugLink: https://bugzilla.kernel.org/show_bug.cgi?id=55571
Link: http://lkml.kernel.org/r/1364203098-17741-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>