qt-4.8: Add a developerBuild option

This option configures qmake with the -developer-build option.
For example, this tells Qt installer to also install Qt's private headers.
See http://doc.qt.digia.com/qt/configure-options.html for more.

pkgs/development/libraries/qt-4.x/4.8/default.nix

@@ -9,6 +9,7 @@
 , buildWebkit ? true
 , flashplayerFix ? false, gdk_pixbuf
 , gtkStyle ? false, libgnomeui, gtk, GConf, gnome_vfs
+, developerBuild ? false
 }:
 
 with stdenv.lib;
@@ -74,6 +75,7 @@ stdenv.mkDerivation rec {
       -nomake demos -nomake examples -nomake docs
 
       -no-phonon ${if buildWebkit then "" else "-no"}-webkit ${if buildMultimedia then "" else "-no"}-multimedia -audio-backend
+      ${if developerBuild then "-developer-build" else ""}
     '';
 
   propagatedBuildInputs =