wined3d: Implement wined3d_surface_flip() as a blit.

This allows us to actually take the "override" parameter into account. Plain
back -> front flips will be detected in wined3d_surface_flip() and will still
be handled by wined3d_swapchain_present().

dlls/wined3d/surface.c

@@ -3807,7 +3807,7 @@ HRESULT CDECL wined3d_surface_flip(struct wined3d_surface *surface, struct wined
             return WINED3D_OK;
     }
 
-    return wined3d_swapchain_present(swapchain, NULL, NULL, swapchain->win_handle, NULL, 0);
+    return wined3d_surface_blt(surface, NULL, override, NULL, 0, NULL, WINED3DTEXF_POINT);
 }
 
 /* Do not call while under the GL lock. */