gnome3.gnome-control-center: hardcode path to gnome-desktop

This is needed for its gnome-version.xml so it can properly display
the current gnome-desktop version in the info panel.
Previously it was always "GNOME 3.0".

pkgs/desktops/gnome-3/core/gnome-control-center/default.nix

@@ -40,6 +40,7 @@ stdenv.mkDerivation rec {
     (substituteAll {
       src = ./paths.patch;
       gcm = gnome-color-manager;
+      gnome_desktop = gnome-desktop;
       inherit glibc libgnomekbd tzdata;
       inherit cups networkmanagerapplet;
     })

pkgs/desktops/gnome-3/core/gnome-control-center/paths.patch

@@ -54,6 +54,19 @@ index 96b25140c..1ad704d4a 100644
 
  typedef struct _TzDB TzDB;
  typedef struct _TzLocation TzLocation;
+diff --git a/panels/info/cc-info-overview-panel.c b/panels/info/cc-info-overview-panel.c
+index 4541986db..da7826bfe 100644
+--- a/panels/info/cc-info-overview-panel.c
++++ b/panels/info/cc-info-overview-panel.c
+@@ -187,7 +187,7 @@ load_gnome_version (char **version,
+   gsize length;
+   g_autoptr(VersionData) data = NULL;
+
+-  if (!g_file_get_contents (DATADIR "/gnome/gnome-version.xml",
++  if (!g_file_get_contents ("@gnome_desktop@/share/gnome/gnome-version.xml",
+                             &contents,
+                             &length,
+                             &error))
 diff --git a/panels/network/connection-editor/net-connection-editor.c b/panels/network/connection-editor/net-connection-editor.c
 index 9390a3308..d30b4a68e 100644
 --- a/panels/network/connection-editor/net-connection-editor.c