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/auth2-kbdint.c b/auth2-kbdint.c
index fae67da..bf75c60 100644
--- a/auth2-kbdint.c
+++ b/auth2-kbdint.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: auth2-kbdint.c,v 1.5 2006/08/03 03:34:41 deraadt Exp $ */
+/* $OpenBSD: auth2-kbdint.c,v 1.7 2014/07/15 15:54:14 millert Exp $ */
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
  *
@@ -36,6 +36,7 @@
 #include "auth.h"
 #include "log.h"
 #include "buffer.h"
+#include "misc.h"
 #include "servconf.h"
 
 /* import */
@@ -56,8 +57,8 @@
 	if (options.challenge_response_authentication)
 		authenticated = auth2_challenge(authctxt, devs);
 
-	xfree(devs);
-	xfree(lang);
+	free(devs);
+	free(lang);
 	return authenticated;
 }