perf scripting python: Use Py_FatalError instead of die()

perf scripting python: Use Py_FatalError instead of die()

It probably is equivalent, but that seems to be the "pythonic" way of
dieing? Anyway, one less die() in the tools/perf codebase.

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Cc: Chris Phlipot <cphlipot0@gmail.com>
Link: http://lkml.kernel.org/n/tip-nlzgepdv2818zs4e7faif9tu@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>