Merge 'staging' into closure-size

- there were many easy merge conflicts
- cc-wrapper needed nontrivial changes

Many other problems might've been created by interaction of the branches,
but stdenv and a few other packages build fine now.

pkgs/development/libraries/libogg/default.nix

@@ -1,10 +1,7 @@
 { stdenv, fetchurl }:
 
-let
+stdenv.mkDerivation rec {
   name = "libogg-1.3.2";
-in
-stdenv.mkDerivation {
-  inherit name;
 
   src = fetchurl {
     url = "http://downloads.xiph.org/releases/ogg/${name}.tar.xz";