New_Connection(): mark "IsSSL" parameter as UNUSED

This fixes the following warning message when building without SSL support:

 conn.c: In function "New_Connection":
 conn.c:1365: warning: unused parameter "IsSSL"

Introduced by commit 01b62202.

src/ngircd/conn.c

@@ -1366,7 +1366,7 @@ Count_Connections(ng_ipaddr_t *a)
  * @returns	Accepted socket descriptor or -1 on error.
  */
 static int
-New_Connection(int Sock, bool IsSSL)
+New_Connection(int Sock, UNUSED bool IsSSL)
 {
 #ifdef TCPWRAP
 	struct request_info req;