perf tools: Instead of redirecting flex output, use -o

This gives us a real filename instead of having '<stdout>' show up all
over the place when debugging.

Signed-off-by: Cody P Schafer <cody@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1396652539-2416-1-git-send-email-cody@linux.vnet.ibm.com


Signed-off-by: Jiri Olsa <jolsa@redhat.com>