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/krl.h b/krl.h
new file mode 100644
index 0000000..4e12bef
--- /dev/null
+++ b/krl.h
@@ -0,0 +1,65 @@
+/*
+ * Copyright (c) 2012 Damien Miller <djm@mindrot.org>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/* $OpenBSD: krl.h,v 1.4 2015/01/13 19:06:49 djm Exp $ */
+
+#ifndef _KRL_H
+#define _KRL_H
+
+/* Functions to manage key revocation lists */
+
+#define KRL_MAGIC		"SSHKRL\n\0"
+#define KRL_FORMAT_VERSION	1
+
+/* KRL section types */
+#define KRL_SECTION_CERTIFICATES	1
+#define KRL_SECTION_EXPLICIT_KEY	2
+#define KRL_SECTION_FINGERPRINT_SHA1	3
+#define KRL_SECTION_SIGNATURE		4
+
+/* KRL_SECTION_CERTIFICATES subsection types */
+#define KRL_SECTION_CERT_SERIAL_LIST	0x20
+#define KRL_SECTION_CERT_SERIAL_RANGE	0x21
+#define KRL_SECTION_CERT_SERIAL_BITMAP	0x22
+#define KRL_SECTION_CERT_KEY_ID		0x23
+
+struct sshkey;
+struct sshbuf;
+struct ssh_krl;
+
+struct ssh_krl *ssh_krl_init(void);
+void ssh_krl_free(struct ssh_krl *krl);
+void ssh_krl_set_version(struct ssh_krl *krl, u_int64_t version);
+void ssh_krl_set_sign_key(struct ssh_krl *krl, const struct sshkey *sign_key);
+int ssh_krl_set_comment(struct ssh_krl *krl, const char *comment);
+int ssh_krl_revoke_cert_by_serial(struct ssh_krl *krl,
+    const struct sshkey *ca_key, u_int64_t serial);
+int ssh_krl_revoke_cert_by_serial_range(struct ssh_krl *krl,
+    const struct sshkey *ca_key, u_int64_t lo, u_int64_t hi);
+int ssh_krl_revoke_cert_by_key_id(struct ssh_krl *krl,
+    const struct sshkey *ca_key, const char *key_id);
+int ssh_krl_revoke_key_explicit(struct ssh_krl *krl, const struct sshkey *key);
+int ssh_krl_revoke_key_sha1(struct ssh_krl *krl, const struct sshkey *key);
+int ssh_krl_revoke_key(struct ssh_krl *krl, const struct sshkey *key);
+int ssh_krl_to_blob(struct ssh_krl *krl, struct sshbuf *buf,
+    const struct sshkey **sign_keys, u_int nsign_keys);
+int ssh_krl_from_blob(struct sshbuf *buf, struct ssh_krl **krlp,
+    const struct sshkey **sign_ca_keys, size_t nsign_ca_keys);
+int ssh_krl_check_key(struct ssh_krl *krl, const struct sshkey *key);
+int ssh_krl_file_contains_key(const char *path, const struct sshkey *key);
+
+#endif /* _KRL_H */
+