Select --vout value from vout display list rather than video output

This fixes the plugin names in the user interface. On the other hand,
legacy video output plugins cannot be selected explicitly anymore
(though they still take part in automatic probing).

src/libvlc-module.c

@@ -1741,7 +1741,7 @@ vlc_module_begin ()
         change_safe()
 
     set_subcategory( SUBCAT_VIDEO_VOUT )
-    add_module( "vout", "video output", NULL, NULL, VOUT_TEXT, VOUT_LONGTEXT,
+    add_module( "vout", "vout display", NULL, NULL, VOUT_TEXT, VOUT_LONGTEXT,
                 true )
         change_short('V')