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: ec685de25b6718f8 ("perf test: Add kernel lock contention test")
Signed-off-by: James Clark <[e-mail]>
Cc: Adrian Hunter <[e-mail]>
Cc: Alexander Shishkin <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Mark Rutland <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/ui/util.c

···
 
 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;
···
 {
 	int ret;
 	va_list args;
+	if (quiet)
+		return 0;
 
 	va_start(args, format);
 	ret = perf_eops->warning(format, args);