tigervnc: correct default ssh client path (#29084)

* tigervnc: correct default ssh client path

The -via command sets up an ssh tunnel, but is hardcoded to /usr/bin/ssh
upstream.  This patches it to use the nixpkgs openssh client.

* tigervnc: patch ssh path correctly

pkgs/tools/admin/tigervnc/default.nix

@@ -5,7 +5,7 @@
 , cmake, gettext, libtool
 , glproto, mesa_glu
 , gnutls, pam, nettle
-, xterm }:
+, xterm, openssh }:
 
 with stdenv.lib;
 
@@ -22,7 +22,7 @@ stdenv.mkDerivation rec {
 
   inherit fontDirectories;
 
-  patchPhase = ''
+  postPatch = ''
     sed -i -e '/^\$cmd \.= " -pn";/a$cmd .= " -xkbdir ${xkeyboard_config}/etc/X11/xkb";' unix/vncserver
     fontPath=
     for i in $fontDirectories; do
@@ -31,6 +31,8 @@ stdenv.mkDerivation rec {
       done
     done
     sed -i -e '/^\$cmd \.= " -pn";/a$cmd .= " -fp '"$fontPath"'";' unix/vncserver
+    substituteInPlace vncviewer/vncviewer.cxx \
+       --replace '"/usr/bin/ssh' '"${openssh}/bin/ssh'
   '';
 
   dontUseCmakeBuildDir = true;