external/openssh: update to 6.8p1.

In preparation for some updates to external/openssh to make it work with
BoringSSL, this change updates the code to a recent version. The current
version (5.9p1) is coming up on four years old now.

  * Confirmed that f5c67b478bef9992de9e9ec91ce10af4f6205e0d matches
    OpenSSH 5.9p1 exactly (save for the removal of the scard
    subdirectory).

  * Downloaded openssh-6.8p1.tar.gz (SHA256:
    3ff64ce73ee124480b5bf767b9830d7d3c03bbcb6abe716b78f0192c37ce160e)
    and verified with PGP signature. (I've verified Damien's key in
    person previously.)

  * Applied changes between f5c67b478bef9992de9e9ec91ce10af4f6205e0d and
    OpenSSH 5.9p1 to 6.8p1 and updated the build as best I can. The
    ugliest change is probably the duplication of umac.c to umac128.c
    because Android conditionally compiles that file twice. See the
    comment in those files.

Change-Id: I63cb07a8118afb5a377f116087a0882914cea486
diff --git a/sshlogin.c b/sshlogin.c
index 54629f7..818312f 100644
--- a/sshlogin.c
+++ b/sshlogin.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: sshlogin.c,v 1.27 2011/01/11 06:06:09 djm Exp $ */
+/* $OpenBSD: sshlogin.c,v 1.31 2015/01/20 23:14:00 deraadt Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -42,7 +42,6 @@
 #include "includes.h"
 
 #include <sys/types.h>
-#include <sys/param.h>
 #include <sys/socket.h>
 
 #include <netinet/in.h>
@@ -54,10 +53,12 @@
 #include <string.h>
 #include <time.h>
 #include <unistd.h>
+#include <limits.h>
 
 #include "loginrec.h"
 #include "log.h"
 #include "buffer.h"
+#include "misc.h"
 #include "servconf.h"
 
 extern Buffer loginmsg;
@@ -87,7 +88,7 @@
 store_lastlog_message(const char *user, uid_t uid)
 {
 #ifndef NO_SSH_LASTLOG
-	char *time_string, hostname[MAXHOSTNAMELEN] = "", buf[512];
+	char *time_string, hostname[HOST_NAME_MAX+1] = "", buf[512];
 	time_t last_login_time;
 
 	if (!options.print_lastlog)
@@ -97,7 +98,7 @@
 	time_string = sys_auth_get_lastlogin_msg(user, uid);
 	if (time_string != NULL) {
 		buffer_append(&loginmsg, time_string, strlen(time_string));
-		xfree(time_string);
+		free(time_string);
 	}
 # else
 	last_login_time = get_last_login_time(uid, user, hostname,