Don't handle impossible error

glXChooseFBConfig always return NULL if there are no adequate configs.
(cherry picked from commit ef48f9b6)

Conflicts:

	modules/video_output/x11/glx.c

modules/video_output/x11/glx.c

@@ -243,10 +243,9 @@ int InitGLX13( vout_thread_t *p_vout )
 
     /* Get the FB configuration */
     p_fbconfs = glXChooseFBConfig( p_sys->p_display, 0, p_attr, &i_nbelem );
-    if( (i_nbelem <= 0) || !p_fbconfs )
+    if( p_fbconfs == NULL )
     {
         msg_Err( p_vout, "Cannot get FB configurations");
-        if( p_fbconfs ) XFree( p_fbconfs );
         return VLC_EGENERIC;
     }
     fbconf = p_fbconfs[0];