perf test: Ensure sample_period is set libpfm4 events

Test that a command line option doesn't override the period set on a
libpfm4 event.

Without libpfm4 test passes as unsupported.
Signed-off-by: Ian Rogers <irogers@google.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Andrii Nakryiko <andriin@fb.com>
Cc: Athira Jajeev <atrajeev@linux.vnet.ibm.com>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: John Fastabend <john.fastabend@gmail.com>
Cc: KP Singh <kpsingh@chromium.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Song Liu <songliubraving@fb.com>
Cc: Stephane Eranian <eranian@google.com>
Cc: Yonghong Song <yhs@fb.com>
Cc: bpf@vger.kernel.org
Cc: netdev@vger.kernel.org
Link: http://lore.kernel.org/lkml/20200728085734.609930-4-irogers@google.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/tests/attr/README

@@ -53,6 +53,7 @@ Following tests are defined (with perf commands):
   perf record -i kill                           (test-record-no-inherit)
   perf record -n kill                           (test-record-no-samples)
   perf record -c 100 -P kill                    (test-record-period)
+  perf record -c 1 --pfm-events=cycles:period=2 (test-record-pfm-period)
   perf record -R kill                           (test-record-raw)
   perf stat -e cycles kill                      (test-stat-basic)
   perf stat kill                                (test-stat-default)

tools/perf/tests/attr/test-record-pfm-period

+[config]
+command = record
+args    = --no-bpf-event -c 10000 --pfm-events=cycles:period=77777 kill >/dev/null 2>&1
+ret     = 1
+
+[event:base-record]
+sample_period=77777
+sample_type=7
+freq=0