Style: Replace header guards with #pragma once

scene/main/timer.h

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef TIMER_H
-#define TIMER_H
+#pragma once
 
 #include "scene/main/node.h"
 
@@ -89,5 +88,3 @@ private:
 };
 
 VARIANT_ENUM_CAST(Timer::TimerProcessCallback);
-
-#endif // TIMER_H