perf script python: Add stub for PMU symbol to the python binding

Fix missing symbol seen in:

  ```
   19: 'import perf' in python                                         :
  --- start ---
  test child forked, pid 2640936
  python usage test: "echo "import sys ; sys.path.insert(0, 'python'); import perf" | '/usr/bin/python3' "
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
  ImportError: tools/perf/python/perf.cpython-311-x86_64-linux-gnu.so: undefined symbol: perf_pmus__supports_extended_type
  test child finished with -1
  ---- end ----
  'import perf' in python: FAILED!
  ```

Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Clark <james.clark@arm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Kan Liang <kan.liang@linux.intel.com>
Cc: Leo Yan <leo.yan@linaro.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yang Jihong <yangjihong1@huawei.com>
Link: https://lore.kernel.org/r/20230810180944.2794188-1-irogers@google.com


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