sshd: remove blacklist call from grace_alarm_timer

Under certain circumstances it may call log(3), which is not async-
signal-safe.

For now just remove the blacklist integration from this path, which
means that blacklistd will not detect and firewall hosts that establish
a connection but do nothing further.

Sponsored by:	The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D46203

crypto/openssh/sshd.c

@@ -377,8 +377,6 @@ grace_alarm_handler(int sig)
 		kill(0, SIGTERM);
 	}
 
-	BLACKLIST_NOTIFY(the_active_state, BLACKLIST_AUTH_FAIL, "ssh");
-
 	/* Log error and exit. */
 	sigdie("Timeout before authentication for %s port %d",
 	    ssh_remote_ipaddr(the_active_state),