perf script python: Fix export-to-postgresql.py occasional failure

Occasional export failures were found to be caused by truncating 64-bit
pointers to 32-bits. Fix by explicitly setting types for all ctype
arguments and results.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/20180911114504.28516-2-adrian.hunter@intel.com


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