mod_websocket: Merge session close handling changes from mod_c2s (bug fixes) This should bring some fixes and general robustness that mod_websocket had missed out on. The duplicated code here is not at all ideal. To prevent this happening again, we should figure out how to have the common logic in a single place, while still being able to do the websocket-specific parts that we need. The main known bug that this fixes is that it's possible for a session to get into a non-destroyable state. For example, if we try to session:close() a hibernating session, then session.conn is nil and the function will simply return without doing anything. In the mod_c2s code we already handle this, and just destroy the session. But if a hibernating websocket session is never resumed or becomes non-resumable, it will become immortal! By merging the fix from mod_c2s, the session should now be correctly destroyed.