Style: Replace header guards with #pragma once

platform/macos/key_mapping_macos.h

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef KEY_MAPPING_MACOS_H
-#define KEY_MAPPING_MACOS_H
+#pragma once
 
 #include "core/os/keyboard.h"
 
@@ -51,5 +50,3 @@ public:
 	static String keycode_get_native_string(Key p_keycode);
 	static unsigned int keycode_get_native_mask(Key p_keycode);
 };
-
-#endif // KEY_MAPPING_MACOS_H