Style: Replace header guards with #pragma once

servers/rendering/shader_include_db.h

@@ -28,8 +28,7 @@
 /* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.                 */
 /**************************************************************************/
 
-#ifndef SHADER_INCLUDE_DB_H
-#define SHADER_INCLUDE_DB_H
+#pragma once
 
 #include "core/object/class_db.h"
 
@@ -49,5 +48,3 @@ public:
 	static String get_built_in_include_file(const String &p_filename);
 	static String parse_include_files(const String &p_code);
 };
-
-#endif // SHADER_INCLUDE_DB_H