perf scripts python: Add Python 3 support to Util.py

Support both Python 2 and Python 3 in Util.py. The dict class no longer
has a ``has_key`` method and print is now a function rather than a
statement. This should have no functional change.

Signed-off-by: Jeremy Cline <jeremy@jcline.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Herton Krzesinski <herton@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/0100016341a730c6-8db8b9b1-da2d-4ee3-96bf-47e0ae9796bd-000000@email.amazonses.com


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