perf script: Pass perf_script into process_event

Passing perf_script struct into process_event function, so we could
process configuration data for event printing.

It will be used in following patch to get event name string width.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20151126175521.GA18979@krava.brq.redhat.com


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