tempfork: temporarily fork gliderlabs/ssh and x/crypto/ssh

While we rearrange/upstream things.

gliderlabs/ssh is forked into tempfork from our prior fork
at https://github.com/tailscale/ssh/commit/be8b7add4057ef5a8e458b42331a7633c06d026a

x/crypto/ssh OTOH is forked at
https://github.com/tailscale/golang-x-crypto because it was gnarlier
to vendor with various internal packages, etc.
Its git history shows where it starts (2c7772ba30643b7a2026cbea938420dce7c6384d).

Updates #3802

Change-Id: I546e5cdf831cfc030a6c42557c0ad2c58766c65f
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

tempfork/gliderlabs/ssh/wrap.go

@@ -0,0 +1,33 @@
+package ssh
+
+import gossh "github.com/tailscale/golang-x-crypto/ssh"
+
+// PublicKey is an abstraction of different types of public keys.
+type PublicKey interface {
+	gossh.PublicKey
+}
+
+// The Permissions type holds fine-grained permissions that are specific to a
+// user or a specific authentication method for a user. Permissions, except for
+// "source-address", must be enforced in the server application layer, after
+// successful authentication.
+type Permissions struct {
+	*gossh.Permissions
+}
+
+// A Signer can create signatures that verify against a public key.
+type Signer interface {
+	gossh.Signer
+}
+
+// ParseAuthorizedKey parses a public key from an authorized_keys file used in
+// OpenSSH according to the sshd(8) manual page.
+func ParseAuthorizedKey(in []byte) (out PublicKey, comment string, options []string, rest []byte, err error) {
+	return gossh.ParseAuthorizedKey(in)
+}
+
+// ParsePublicKey parses an SSH public key formatted for use in
+// the SSH wire protocol according to RFC 4253, section 6.6.
+func ParsePublicKey(in []byte) (out PublicKey, err error) {
+	return gossh.ParsePublicKey(in)
+}