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/deattack.h b/deattack.h
index 0316fb2..ce67a30 100644
--- a/deattack.h
+++ b/deattack.h
@@ -1,4 +1,4 @@
-/* $OpenBSD: deattack.h,v 1.10 2006/09/16 19:53:37 djm Exp $ */
+/* $OpenBSD: deattack.h,v 1.11 2015/01/19 19:52:16 markus Exp $ */
 
 /*
  * Cryptographic attack detector for ssh - Header file
@@ -26,6 +26,13 @@
 #define DEATTACK_OK		0
 #define DEATTACK_DETECTED	1
 #define DEATTACK_DOS_DETECTED	2
+#define DEATTACK_ERROR		3
 
-int	 detect_attack(u_char *, u_int32_t);
+struct deattack_ctx {
+	u_int16_t *h;
+	u_int32_t n;
+};
+
+void	 deattack_init(struct deattack_ctx *);
+int	 detect_attack(struct deattack_ctx *, const u_char *, u_int32_t);
 #endif