Add recurseForRelease flag

I don't want kde-4.5 to be visible for nix-env, but I want hydra to build it

svn path=/nixpkgs/trunk/; revision=22930

pkgs/desktops/kde-4.5/default.nix

@@ -1,6 +1,7 @@
 callPackage :
 
 {
+  recurseForRelease = true;
 
 ### SUPPORT
   akonadi = callPackage ./support/akonadi { };

pkgs/top-level/release-lib.nix

@@ -104,7 +104,9 @@ rec {
     
   # May fail as much as it wishes, we will catch the error.
   processPackage = attrSet: 
-    if attrSet ? recurseForDerivations && attrSet.recurseForDerivations then 
+    if attrSet ? recurseForDerivations && attrSet.recurseForDerivations then
+      packagesWithMetaPlatform attrSet
+    else if attrSet ? recurseForRelease && attrSet.recurseForRelease then
       packagesWithMetaPlatform attrSet
     else
       if attrSet ? meta && attrSet.meta ? platforms