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/roaming.h b/roaming.h
index 6bb94cc..da069f8 100644
--- a/roaming.h
+++ b/roaming.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: roaming.h,v 1.5 2009/10/24 11:11:58 andreas Exp $ */
+/* $OpenBSD: roaming.h,v 1.6 2011/12/07 05:44:38 djm Exp $ */
 /*
  * Copyright (c) 2004-2009 AppGate Network Security AB
  *
@@ -18,8 +18,9 @@
 #ifndef ROAMING_H
 #define ROAMING_H
 
-#define DEFAULT_ROAMBUF 65536
-#define ROAMING_REQUEST "roaming@appgate.com"
+#define DEFAULT_ROAMBUF	65536
+#define MAX_ROAMBUF	(2*1024*1024) /* XXX arbitrary */
+#define ROAMING_REQUEST	"roaming@appgate.com"
 
 extern int roaming_enabled;
 extern int resume_in_progress;