[x11] Remove a useless forced paint

We force the redraw before mapping, in the hope that when a composited
window manager maps the window it will have its contents ready; that is
not going to work: the solution for this problem requires the implementation
of a protocol for compositors, and not a hack.

Moreover, painting before mapping will cause a paint with the wrong
GL viewport size, which is the wrong thing to do on GLX.

clutter/x11/clutter-stage-x11.c

@@ -542,11 +542,6 @@ clutter_stage_x11_show (ClutterStageWindow *stage_window,
 
       clutter_actor_map (CLUTTER_ACTOR (stage_x11->wrapper));
 
-      /* we force a redraw here, so that by the time we have
-       * been mapped, the window has contents
-       */
-      _clutter_do_redraw (CLUTTER_STAGE (stage_x11->wrapper));
-
       XMapWindow (stage_x11->xdpy, stage_x11->xwin);
     }
 }