switch to meson build + refactor code to remove compile warning

output.c

@@ -11,6 +11,7 @@
 
 static void output_frame(struct wl_listener *listener, void *data)
 {
+    (void) data;
     /* This function is called every time an output is ready to display a frame,
      * generally at the output's refresh rate (e.g. 60Hz). */
     struct diyac_output *output = wl_container_of(listener, output, frame);
@@ -39,6 +40,7 @@ static void output_request_state(struct wl_listener *listener, void *data)
 
 static void output_destroy(struct wl_listener *listener, void *data)
 {
+    (void)data;
     struct diyac_output *output = wl_container_of(listener, output, destroy);
     if(output->lock_handle)
     {