spearmint: OpenGL2: Fix marks on brushes in second player's view

This was fixed in the opengl1 renderer in 2015 in the commit
"spearmint: Fix marks on brushes in second player's view"
52fe5b7.

code/renderergl2/tr_scene.c

@@ -423,7 +423,7 @@ void RE_AddRefEntityToScene( const refEntity_t *ent, int entBufSize, int numVert
 		model_t *model = R_GetModelByHandle( ent->hModel );
 
 		if ( model && model->type == MOD_BRUSH ) {
-			model->bmodel->entityNum = r_numentities;
+			model->bmodel->entityNum = r_numentities - r_firstSceneEntity;
 		}
 	}