perf trace/scripting: Check return val of perl_run()

The return value from perl_run() is currently ignored, but it
should be checked and used to exit perf if there are problems
loading the script.

Signed-off-by: Tom Zanussi <tzanussi@gmail.com>
Cc: fweisbec@gmail.com
Cc: rostedt@goodmis.org
LKML-Reference: <1260867220-15699-4-git-send-email-tzanussi@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>