Remove outdated ircprintf prototype from commands.cc.

commands.cc

@@ -30,7 +30,6 @@ int dispatch_command(struct server *server, const char *cmdname, int argc, char
 }
 
 void do_copyover(char *);
-void ircprintf(const char *format, ...);
 _COMMAND(copyover) {
 	do_copyover(state->sender->nick);
 	return 0;