perf script: Add --[no-]-demangle/--[no-]-demangle-kernel

Sometimes when post-processing output from `perf script` one does not
want to demangle C++ symbol names. Add an option to allow this.

Also add --[no-]demangle-kernel to be consistent with top/report/probe.

Signed-off-by: Mark Drayton <mbd@fb.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1440616695-32340-1-git-send-email-scientist@fb.com


Signed-off-by: Yannick Brosseau <scientist@fb.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>