compositor-wayland: Properly dealloc mmap data using munmap

Signed-off-by: Raúl Peñacoba <raul.mikaop.zelda@gmail.com>
Reviewed-by: Quentin Glidic <sardemff7+git@sardemff7.net>

libweston/compositor-wayland.c

@@ -301,7 +301,7 @@ wayland_output_get_shm_buffer(struct wayland_output *output)
 	if (sb == NULL) {
 		weston_log("could not zalloc %zu memory for sb: %m\n", sizeof *sb);
 		close(fd);
-		free(data);
+		munmap(data, height * stride);
 		return NULL;
 	}