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/ssh-pkcs11-helper.8 b/ssh-pkcs11-helper.8
index 9bdaadc..3728c4e 100644
--- a/ssh-pkcs11-helper.8
+++ b/ssh-pkcs11-helper.8
@@ -1,4 +1,4 @@
-.\" $OpenBSD: ssh-pkcs11-helper.8,v 1.3 2010/02/10 23:20:38 markus Exp $
+.\" $OpenBSD: ssh-pkcs11-helper.8,v 1.4 2013/07/16 00:07:52 schwarze Exp $
 .\"
 .\" Copyright (c) 2010 Markus Friedl.  All rights reserved.
 .\"
@@ -14,7 +14,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: February 10 2010 $
+.Dd $Mdocdate: July 16 2013 $
 .Dt SSH-PKCS11-HELPER 8
 .Os
 .Sh NAME
@@ -40,4 +40,4 @@
 first appeared in
 .Ox 4.7 .
 .Sh AUTHORS
-.An Markus Friedl Aq markus@openbsd.org
+.An Markus Friedl Aq Mt markus@openbsd.org