Remove the XmppComponent::last_auth bool that was never used anywhere

src/xmpp/xmpp_component.cpp

@@ -39,7 +39,6 @@ static std::set<std::string> kickable_errors{
 XmppComponent::XmppComponent(std::shared_ptr<Poller> poller, const std::string& hostname, const std::string& secret):
   TCPSocketHandler(poller),
   ever_auth(false),
-  last_auth(false),
   served_hostname(hostname),
   secret(secret),
   authenticated(false),
@@ -169,7 +168,6 @@ void XmppComponent::on_remote_stream_open(const XmlNode& node)
       return ;
     }
 
-  this->last_auth = false;
   // Try to authenticate
   char digest[HASH_LENGTH * 2 + 1];
   sha1nfo sha1;
@@ -277,7 +275,6 @@ void XmppComponent::handle_handshake(const Stanza& stanza)
   (void)stanza;
   this->authenticated = true;
   this->ever_auth = true;
-  this->last_auth = true;
   log_info("Authenticated with the XMPP server");
 #ifdef SYSTEMDDAEMON_FOUND
   sd_notify(0, "READY=1");