libssh: temporarily patch to fix x2goclient

See <https://red.libssh.org/issues/194>:

  "In libssh 0.7.0, ssh_forward_listen() is present in the headers as
  a deprecated function, but it is not actually present in the code.
  This appears to have been introduced in commit 5229253f."

pkgs/development/libraries/libssh/0001-Reintroduce-ssh_forward_listen-Fixes-194.patch

@@ -0,0 +1,28 @@
+From 3c8fe6e2c595ee019408249c364b3019b6c31a8a Mon Sep 17 00:00:00 2001
+From: Mike DePaulo <mikedep333@gmail.com>
+Date: Fri, 15 May 2015 22:22:13 -0400
+Subject: [PATCH] Reintroduce ssh_forward_listen() (Fixes: #194)
+
+---
+ src/channels.c | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/src/channels.c b/src/channels.c
+index 7a4e71f..db5f83a 100644
+--- a/src/channels.c
++++ b/src/channels.c
+@@ -2206,6 +2206,11 @@ error:
+ }
+ 
+ /* DEPRECATED */
++int ssh_forward_listen(ssh_session session, const char *address, int port, int *bound_port) {
++  return ssh_channel_listen_forward(session, address, port, bound_port);
++}
++
++/* DEPRECATED */
+ ssh_channel ssh_forward_accept(ssh_session session, int timeout_ms) {
+   return ssh_channel_accept(session, SSH_CHANNEL_FORWARDED_TCPIP, timeout_ms, NULL);
+ }
+-- 
+2.1.4
+

pkgs/development/libraries/libssh/default.nix

@@ -34,6 +34,8 @@ stdenv.mkDerivation rec {
     sha256 = "1wfrdqhv97f4ycd9bcpgb6gw47kr7b2iq8cz5knk8a6n9c6870k0";
   };
 
+  patches = [ ./0001-Reintroduce-ssh_forward_listen-Fixes-194.patch ];
+
   postPatch = ''
     # Fix headers to use libsodium instead of NaCl
     sed -i 's,nacl/,sodium/,g' ./include/libssh/curve25519.h src/curve25519.c