Support both Python2 and Python3 in the intel-pt-events.py script

There may be differences in the ordering of output lines due to
differences in dictionary ordering etc.  However the format within lines
should be unchanged.

The use of 'from __future__' implies the minimum supported Python2 version
is now v2.6
Signed-off-by: Tony Jones <tonyj@suse.de>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Link: http://lkml.kernel.org/r/fd26acf9-0c0f-717f-9664-a3c33043ce19@suse.deSigned-off-by: Seeteena Thoufeek <s1seetee@linux.vnet.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>