[client] egl: use eglSwapBuffersWithDamageKHR for cursor-only updates

Instead of damaging the entire surface when rendering a cursor move,
we can use the EGL_KHR_swap_buffers_with_damage extension to only
damage the part of the window covered by the cursor. This should
reduce the cursor movement latency on Wayland.

client/displayservers/Wayland/window.c

@@ -114,5 +114,3 @@ bool waylandIsValidPointerPos(int x, int y)
 {
   return x >= 0 && x < wlWm.width && y >= 0 && y < wlWm.height;
 }
-
-