perf tests metric-only perf stat: Fix tests 84 and 86 s390

On s390x KVM and z/VM machines the CPU Measurement Facility is not
available. Events cycles and instructions do not exist. Running above
tests on s390 KVM and z/VM guests always fail with this error:

# ./perf test 84 86
84: perf stat JSON output linter : FAILED!
86: perf stat STD output linter : FAILED!
#

Root cause is command:

# perf stat -j --metric-only -e instructions,cycles -- true
{"metric-value" : "none"}
#

Which fails due to unsupported events and returns "none".
Do not execute this test case on s390 KVM and z/VM machines.

Output after:
# ./perf test 84 86
84: perf stat JSON output linter : Ok
86: perf stat STD output linter : Ok
#

Fixes: 45a86d017adf4d6c ("perf test: Add --metric-only to perf stat output tests")
Suggested-by: Heiko Carstens <[e-mail]>
Suggested-by: Sumanth Korikkar <[e-mail]>
Reviewed-by: Sumanth Korikkar <[e-mail]>
Signed-off-by: Thomas Richter <[e-mail]>
Cc: Alexander Gordeev <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/shell/lib/stat_output.sh

···
 check_metric_only()
 {
 	echo -n "Checking $1 output: metric only "
+	if [ "$(uname -m)" = "s390x" ] && ! grep '^facilities' /proc/cpuinfo  | grep -qw 67
+	then
+		echo "[Skip] CPU-measurement counter facility not installed"
+		return
+	fi
 	perf stat --metric-only $2 -e instructions,cycles true
 	commachecker --metric-only
 	echo "[Success]"

tools/perf/tests/shell/stat+json_output.sh

···
 check_metric_only()
 {
 	echo -n "Checking json output: metric only "
+	if [ "$(uname -m)" = "s390x" ] && ! grep '^facilities' /proc/cpuinfo  | grep -qw 67
+	then
+		echo "[Skip] CPU-measurement counter facility not installed"
+		return
+	fi
 	perf stat -j --metric-only -e instructions,cycles -o "${stat_output}" true
 	$PYTHON $pythonchecker --metric-only --file "${stat_output}"
 	echo "[Success]"