Playlist: create playlist-autostart just once

(cherry picked from commit da59205e44a1d105ad020cd9a94f8e37e6a012c7)

src/playlist/engine.c

@@ -309,6 +309,7 @@ static void VariablesInit( playlist_t *p_playlist )
     var_SetInteger( p_playlist, "activity", 0 );
 
     /* Variables to control playback */
+    var_Create( p_playlist, "playlist-autostart", VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
     var_Create( p_playlist, "play-and-stop", VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
     var_Create( p_playlist, "play-and-exit", VLC_VAR_BOOL | VLC_VAR_DOINHERIT );
     var_Create( p_playlist, "random", VLC_VAR_BOOL | VLC_VAR_DOINHERIT );

src/playlist/item.c

@@ -64,7 +64,7 @@ static void input_item_add_subitem_tree ( const vlc_event_t * p_event,
     assert( p_item != NULL );
 
     bool b_current = get_current_status_item( p_playlist ) == p_item;
-    bool b_autostart = var_CreateGetBool( p_playlist, "playlist-autostart" );
+    bool b_autostart = var_GetBool( p_playlist, "playlist-autostart" );
     bool b_stop = p_item->i_flags & PLAYLIST_SUBITEM_STOP_FLAG;
     bool b_flat = false;