perf dlfilter: Add a test for object_code()

Extend the "dlfilter C API" test to test
perf_dlfilter_fns.object_code().

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Link: https://lore.kernel.org/r/20230928091033.33998-1-adrian.hunter@intel.com
Signed-off-by: Namhyung Kim <namhyung@kernel.org>

perf dlfilter: Add al_cleanup()

Add perf_dlfilter_fns.al_cleanup() to do addr_location__exit() on data
passed via perf_dlfilter_fns.resolve_address().

Add dlfilter-test-api-v2 to the "dlfilter C API" test to test it.

Update documentation, clarifying that data returned by APIs should not
be dereferenced after filter_event() and filter_event_early() return.

Fixes: 0dd5041c9a0eaf8c ("perf addr_location: Add init/exit/copy functions")
Reviewed-by: Ian Rogers <irogers@google.com>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: https://lore.kernel.org/r/20230731091857.10681-3-adrian.hunter@intel.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>