Style: Replace header guards with #pragma once

scene/3d/skeleton_ik_3d.h

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef SKELETON_IK_3D_H
-#define SKELETON_IK_3D_H
+#pragma once
 
 #include "scene/3d/skeleton_modifier_3d.h"
 
@@ -191,5 +190,3 @@ private:
 	void reload_goal();
 	void _solve_chain();
 };
-
-#endif // SKELETON_IK_3D_H