perf tools: Fix "kernel lock contention analysis" test by not printing warnings in quiet mode

Especially when CONFIG_LOCKDEP and other debug configs are enabled,
Perf can print the following warning when running the "kernel lock
contention analysis" test:

  Warning:
  Processed 1378918 events and lost 4 chunks!

  Check IO/CPU overload!

  Warning:
  Processed 4593325 samples and lost 70.00%!

The test already supplies -q to run in quiet mode, so extend quiet mode
to perf_stdio__warning() and also ui__warning() for consistency.

This fixes the following failure due to the extra lines counted:

  perf test "lock cont" -vvv

  82: kernel lock contention analysis test                            :
  --- start ---
  test child forked, pid 3125
  Testing perf lock record and perf lock contention
  [Fail] Recorded result count is not 1: 9
  test child finished with -1
  ---- end ----
  kernel lock contention analysis test: FAILED!

Fixes: ec685de2 ("perf test: Add kernel lock contention test")
Signed-off-by: James Clark <james.clark@arm.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Ian Rogers <irogers@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: https://lore.kernel.org/r/20221018094137.783081-2-james.clark@arm.comSigned-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

tools/perf/ui/util.c

@@ -15,6 +15,9 @@ static int perf_stdio__error(const char *format, va_list args)
 
 static int perf_stdio__warning(const char *format, va_list args)
 {
+	if (quiet)
+		return 0;
+
 	fprintf(stderr, "Warning:\n");
 	vfprintf(stderr, format, args);
 	return 0;
@@ -45,6 +48,8 @@ int ui__warning(const char *format, ...)
 {
 	int ret;
 	va_list args;
+	if (quiet)
+		return 0;
 
 	va_start(args, format);
 	ret = perf_eops->warning(format, args);