tests: fix leak in events

Fixes all the ASan reported leaks in this test.

Signed-off-by: Pekka Paalanen <pekka.paalanen@collabora.com>

tests/event-test.c

@@ -108,6 +108,8 @@ TEST(test_surface_output)
 	/* visible */
 	check_client_move(client, x, --y);
 	assert(output_contains_client(client));
+
+	client_destroy(client);
 }
 
 static void
@@ -176,4 +178,9 @@ TEST(buffer_release)
 	assert(buf1_released == 0);
 	assert(buf2_released == 1);
 	assert(buf3_released == 1);
+
+	buffer_destroy(buf1);
+	buffer_destroy(buf2);
+	buffer_destroy(buf3);
+	client_destroy(client);
 }