wall.c: set the total output aspect ratio to the device aspect ratio, even

if size constrains stoped us from making the parts have that aspect ratio.
This causes a slight stretch of the image in some direction but should
totally remove black lines between the elements.
todo:
 * make device aspect ratio configureable (easy)
 * handle anamorphic input video (medium)

modules/video_filter/wall.c

@@ -355,7 +355,8 @@ static int Init( vout_thread_t *p_vout )
             p_vout->p_sys->pp_vout[ p_vout->p_sys->i_vout ].p_vout =
                 vout_Create( p_vout, i_width, i_height,
                              p_vout->render.i_chroma,
-                             VOUT_ASPECT_FACTOR * i_width / i_height );
+                             i_aspect * i_target_height / i_height *
+                             i_width / i_target_width );
             if( p_vout->p_sys->pp_vout[ p_vout->p_sys->i_vout ].p_vout == NULL )
             {
                 msg_Err( p_vout, "failed to get %ix%i vout threads",