PredefChannelsOnly: Fix message for non pre-defined channels

If PredefChannelsOnly is enabled, and if someone tries to create
a channel which does not exist, then the error message is a 474.
The 474 Error message changed recently and does not match anymore:
'Cannot join channel (+b) -- You are banned'.

Changed the error message to numeric 403 'No such channel'.

Bug introduced by commit 9a82304a.

(cherry picked from commit 2c2e08f34187a33c1da745995c5f213e33a91410)

src/ngircd/irc-channel.c

@@ -365,7 +365,7 @@ IRC_JOIN( CLIENT *Client, REQUEST *Req )
 		chan = Channel_Search(channame);
 		if (!chan && Conf_PredefChannelsOnly) {
 			 /* channel must be created, but forbidden by config */
-			IRC_WriteStrClient(Client, ERR_BANNEDFROMCHAN_MSG,
+			IRC_WriteStrClient(Client, ERR_NOSUCHCHANNEL_MSG,
 					   Client_ID(Client), channame);
 			goto join_next;
 		}