clutter: Drop _clutter_util_rectangle_offset

It is only used once so there is no need to port it to Mtk

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/3128>

clutter/clutter/clutter-private.h

@@ -206,11 +206,6 @@ CLUTTER_EXPORT
 void _clutter_util_rectangle_int_extents (const graphene_rect_t *src,
                                           MtkRectangle          *dest);
 
-void _clutter_util_rectangle_offset (const MtkRectangle          *src,
-                                     int                          x,
-                                     int                          y,
-                                     MtkRectangle                *dest);
-
 CLUTTER_EXPORT
 PangoDirection _clutter_pango_unichar_direction (gunichar ch);
 

clutter/clutter/clutter-stage-view.c

@@ -278,10 +278,8 @@ paint_transformed_framebuffer (ClutterStageView     *view,
       MtkRectangle dst_rect;
 
       cairo_region_get_rectangle (redraw_clip, i, &src_rect);
-      _clutter_util_rectangle_offset (&src_rect,
-                                      -view_layout.x,
-                                      -view_layout.y,
-                                      &src_rect);
+      src_rect.x -= view_layout.x;
+      src_rect.y -= view_layout.y;
 
       clutter_stage_view_transform_rect_to_onscreen (view,
                                                      &src_rect,

clutter/clutter/clutter-util.c

@@ -135,18 +135,6 @@ _clutter_util_rectangle_int_extents (const graphene_rect_t *src,
   };
 }
 
-void
-_clutter_util_rectangle_offset (const MtkRectangle *src,
-                                int                 x,
-                                int                 y,
-                                MtkRectangle       *dest)
-{
-  *dest = *src;
-
-  dest->x += x;
-  dest->y += y;
-}
-
 typedef struct
 {
   GType value_type;