perf scripts: Add --symbols option to handle specific symbols

Since perf script no longer only handle the trace points, we can add the
symbol filter option so that scripts can handle specified samples.

Signed-off-by: Feng Tang <feng.tang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1347007349-3102-3-git-send-email-feng.tang@intel.com


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