perf script python: Correct handler check and spelling errors

Correct the checking for handler returned by PyDict_GetItemString(),
also fix some spelling error and remove some data code in
event_analyzing_sample.py, as suggested by Namhyung Kim.

v2: restore back the wrongly removed trace_unhandled() func

Signed-off-by: Feng Tang <feng.tang@intel.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Robert Richter <robert.richter@amd.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/20120809134613.067104c4@feng-i7
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>