disable auto-detected introspection for libwnck and clutter

Didn't build as it was, and not needed anywhere AFAIK.

pkgs/development/libraries/clutter/default.nix

@@ -15,6 +15,8 @@ stdenv.mkDerivation {
       atk json_glib
     ];
 
+  configureFlags = [ "--disable-introspection" ]; # not needed anywhere AFAIK
+
   meta = {
     description = "Clutter, a library for creating fast, dynamic graphical user interfaces";
 

pkgs/development/libraries/libwnck/default.nix

@@ -9,4 +9,6 @@ stdenv.mkDerivation {
   };
 
   buildInputs = [ pkgconfig libX11 gtk intltool ];
+
+  configureFlags = [ "--disable-introspection" ]; # not needed anywhere AFAIK
 }