Only draw cm_patch/bot debug polygons in world scenes

Fixes debug polygons appearing in HUD head model scene.

code/renderergl1/tr_main.c

@@ -1332,6 +1332,9 @@ Visualization aid for movement clipping debugging
 ====================
 */
 void R_DebugGraphics( void ) {
+	if ( tr.refdef.rdflags & RDF_NOWORLDMODEL ) {
+		return;
+	}
 	if ( !r_debugSurface->integer ) {
 		return;
 	}

code/renderergl2/tr_main.c

@@ -1715,6 +1715,9 @@ Visualization aid for movement clipping debugging
 ====================
 */
 void R_DebugGraphics( void ) {
+	if ( tr.refdef.rdflags & RDF_NOWORLDMODEL ) {
+		return;
+	}
 	if ( !r_debugSurface->integer ) {
 		return;
 	}