Drop gdk_cairo_surface_upload_to_gl() helper

There is nothing really special about this code, its just a helper for
uploading pixel data to opengl, and we're not really in the business
of doing opengl-specific helper functions.

docs/reference/gdk/gdk4-sections.txt

@@ -300,7 +300,6 @@ gdk_cairo_rectangle
 gdk_cairo_region
 gdk_cairo_region_create_from_surface
 gdk_cairo_draw_from_gl
-gdk_cairo_surface_upload_to_gl
 </SECTION>
 
 <SECTION>

gdk/gdkcairo.h

@@ -61,13 +61,6 @@ void       gdk_cairo_draw_from_gl (cairo_t              *cr,
                                    int                   width,
                                    int                   height);
 
-GDK_AVAILABLE_IN_ALL
-void      gdk_cairo_surface_upload_to_gl (cairo_surface_t *surface,
-                                          int              target,
-                                          int              width,
-                                          int              height,
-                                          GdkGLContext    *context);
-
 G_END_DECLS
 
 #endif /* __GDK_CAIRO_H__ */

gdk/gdkgl.c

@@ -438,52 +438,3 @@ out:
   if (clip_region)
     cairo_region_destroy (clip_region);
 }
-
-/**
- * gdk_cairo_surface_upload_to_gl:
- * @surface: a Cairo surface
- * @target: a GL texture target
- * @width: the width of the texture @target
- * @height: the height of the texture @target
- * @context: (nullable): a #GdkGLContext, or %NULL to use the currently
- *   bound context
- *
- * Uploads the contents of a Cairo @surface to a GL texture @target.
- */
-void
-gdk_cairo_surface_upload_to_gl (cairo_surface_t *surface,
-                                int              target,
-                                int              width,
-                                int              height,
-                                GdkGLContext    *context)
-{
-  cairo_rectangle_int_t rect;
-  cairo_surface_t *tmp;
-  double device_x_offset, device_y_offset;
-
-  g_return_if_fail (surface != NULL);
-  g_return_if_fail (context == NULL || GDK_IS_GL_CONTEXT (context));
-
-  if (context == NULL)
-    context = gdk_gl_context_get_current ();
-
-  cairo_surface_flush (surface);
-
-  cairo_surface_get_device_offset (surface, &device_x_offset, &device_y_offset);
-
-  rect.x = (int) device_x_offset;
-  rect.y = (int) device_y_offset;
-  rect.width = width;
-  rect.height = height;
-  tmp = cairo_surface_map_to_image (surface, &rect);
-
-  gdk_gl_context_upload_texture (context,
-                                 cairo_image_surface_get_data (tmp),
-                                 rect.width,
-                                 rect.height,
-                                 cairo_image_surface_get_stride (tmp),
-                                 GDK_MEMORY_DEFAULT,
-                                 target);
-
-  cairo_surface_unmap_image (surface, tmp);
-}