btrfs-progs: tests: don't treat segfault as ignorable error

Some fuzzed images cause various tools to crash but the mayfail helper
would not recognize that. We don't mind if the utility failes but it
must not crash.

Signed-off-by: David Sterba <dsterba@suse.com>

tests/common

@@ -48,6 +48,8 @@ run_check_stdout()
 # same as run_check but does not fail the test, output is logged
 run_mayfail()
 {
+	local ret
+
 	echo "############### $@" >> $RESULTS 2>&1
 	if [ "$TEST_LOG" = 'tty' ]; then echo "CMD(mayfail): $@" > /dev/tty; fi
 	if [ "$1" = 'root_helper' ]; then
@@ -55,9 +57,13 @@ run_mayfail()
 	else
 		$INSTRUMENT "$@" >> $RESULTS 2>&1
 	fi
-	if [ $? != 0 ]; then
-		echo "failed (ignored): $@" >> $RESULTS
-		return 1
+	ret=$?
+	if [ $ret != 0 ]; then
+		echo "failed (ignored, ret=$ret): $@" >> $RESULTS
+		if [ $ret == 139 ]; then
+			_fail "mayfail: returned code 139 (SEGFAULT), not ignored"
+		fi
+		return $ret
 	fi
 }