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/ssh2.h b/ssh2.h
index 51a963c..59417e6 100644
--- a/ssh2.h
+++ b/ssh2.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: ssh2.h,v 1.14 2010/08/31 11:54:45 djm Exp $ */
+/* $OpenBSD: ssh2.h,v 1.15 2014/01/29 06:18:35 djm Exp $ */
 
 /*
  * Copyright (c) 2000 Markus Friedl.  All rights reserved.
@@ -115,12 +115,6 @@
 #define SSH2_MSG_USERAUTH_PASSWD_CHANGEREQ		60
 #define SSH2_MSG_USERAUTH_INFO_REQUEST			60
 #define SSH2_MSG_USERAUTH_INFO_RESPONSE			61
-#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP1		60
-#define SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP1		61
-#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_STEP2		62
-#define SSH2_MSG_USERAUTH_JPAKE_SERVER_STEP2		63
-#define SSH2_MSG_USERAUTH_JPAKE_CLIENT_CONFIRM		64
-#define SSH2_MSG_USERAUTH_JPAKE_SERVER_CONFIRM		65
 
 /* connection protocol: generic */