nixos: Replace pkgs.openssh with config.programs.ssh.package

nixos/modules/config/system-path.nix

···
       pkgs.nano
       pkgs.ncurses
       pkgs.netcat
-      pkgs.openssh
+      config.programs.ssh.package
       pkgs.perl
       pkgs.procps
       pkgs.rsync

nixos/modules/services/continuous-integration/jenkins/default.nix

···
       };
 
       packages = mkOption {
-        default = [ pkgs.stdenv pkgs.git pkgs.jdk pkgs.openssh pkgs.nix ];
+        default = [ pkgs.stdenv pkgs.git pkgs.jdk config.programs.ssh.package pkgs.nix ];
         type = types.listOf types.package;
         description = ''
           Packages to add to PATH for the jenkins process.

nixos/modules/services/misc/gitolite.nix

···
       serviceConfig.Type = "oneshot";
       serviceConfig.RemainAfterExit = true;
 
-      path = [ pkgs.gitolite pkgs.git pkgs.perl pkgs.bash pkgs.openssh ];
+      path = [ pkgs.gitolite pkgs.git pkgs.perl pkgs.bash config.programs.ssh.package ];
       script = ''
         cd ${cfg.dataDir}
         mkdir -p .gitolite/logs

nixos/modules/services/misc/nix-daemon.nix

···
     systemd.sockets.nix-daemon.wantedBy = [ "sockets.target" ];
 
     systemd.services.nix-daemon =
-      { path = [ nix pkgs.openssl pkgs.utillinux pkgs.openssh ]
+      { path = [ nix pkgs.openssl pkgs.utillinux config.programs.ssh.package ]
           ++ optionals cfg.distributedBuilds [ pkgs.gzip ];
 
         environment = cfg.envVars

nixos/modules/virtualisation/ec2-data.nix

···
             # can obtain it securely by parsing the output of
             # ec2-get-console-output.
             echo "-----BEGIN SSH HOST KEY FINGERPRINTS-----" > /dev/console
-            ${pkgs.openssh}/bin/ssh-keygen -l -f /etc/ssh/ssh_host_dsa_key.pub > /dev/console
+            ${config.programs.ssh.package}/bin/ssh-keygen -l -f /etc/ssh/ssh_host_dsa_key.pub > /dev/console
             echo "-----END SSH HOST KEY FINGERPRINTS-----" > /dev/console
           '';
         serviceConfig.Type = "oneshot";

nixos/modules/virtualisation/nova.nix

···
 
         # `openssl' is required to generate the CA.  `openssh' is
         # required to generate key pairs.
-        path = [ pkgs.openssl pkgs.openssh pkgs.bash ];
+        path = [ pkgs.openssl config.programs.ssh.package pkgs.bash ];
 
         respawn = false;