perf test: Add test for branch stack sampling

perf test: Add test for branch stack sampling

Add a self test for branch stack sampling, to check that we get the
expected branch types, and filters behave as expected.

Suggested-by: Anshuman Khandual <anshuman.khandual@arm.com>
Signed-off-by: German Gomez <german.gomez@arm.com>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/r/20220705150511.473919-2-german.gomez@arm.com
Tested-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>