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/monitor_fdpass.c b/monitor_fdpass.c
index 7eb6f5c..2ddd807 100644
--- a/monitor_fdpass.c
+++ b/monitor_fdpass.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: monitor_fdpass.c,v 1.19 2010/01/12 00:58:25 djm Exp $ */
+/* $OpenBSD: monitor_fdpass.c,v 1.20 2015/02/25 23:05:47 djm Exp $ */
 /*
  * Copyright 2001 Niels Provos <provos@citi.umich.edu>
  * All rights reserved.
@@ -34,12 +34,17 @@
 #endif
 
 #include <errno.h>
-#ifdef HAVE_POLL_H
-#include <poll.h>
-#endif
 #include <string.h>
 #include <stdarg.h>
 
+#ifdef HAVE_POLL_H
+# include <poll.h>
+#else
+# ifdef HAVE_SYS_POLL_H
+#  include <sys/poll.h>
+# endif
+#endif
+
 #include "log.h"
 #include "monitor_fdpass.h"
 
@@ -65,6 +70,7 @@
 	msg.msg_accrights = (caddr_t)&fd;
 	msg.msg_accrightslen = sizeof(fd);
 #else
+	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
 	msg.msg_control = (caddr_t)&cmsgbuf.buf;
 	msg.msg_controllen = sizeof(cmsgbuf.buf);
 	cmsg = CMSG_FIRSTHDR(&msg);
@@ -131,6 +137,7 @@
 	msg.msg_accrights = (caddr_t)&fd;
 	msg.msg_accrightslen = sizeof(fd);
 #else
+	memset(&cmsgbuf, 0, sizeof(cmsgbuf));
 	msg.msg_control = &cmsgbuf.buf;
 	msg.msg_controllen = sizeof(cmsgbuf.buf);
 #endif