Perform mesh animation only once per frame.

src/clientmap.cpp

@@ -470,7 +470,7 @@ void ClientMap::renderMap(video::IVideoDriver* driver, s32 pass)
			continue;

		// Mesh animation
		{
		if (pass == scene::ESNRP_SOLID) {
			//MutexAutoLock lock(block->mesh_mutex);
			MapBlockMesh *mapBlockMesh = block->mesh;
			assert(mapBlockMesh);