perf script: Add support for PERF_TYPE_RAW

perf script: Add support for PERF_TYPE_RAW

Useful for getting stack traces for hardware events not handled by
PERF_TYPE_HARDWARE.

Cc: Frederic Weisbecker <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Mike Galbraith <[email protected]>
Cc: Paul Mackerras <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Stephane Eranian <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Tom Zanussi <[email protected]>
Signed-off-by: Arun Sharma <[email protected]>
Link: http://lkml.kernel.org/n/[email protected]
Signed-off-by: Arnaldo Carvalho de Melo <[email protected]>