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/libelf/default.nix

@@ -1,4 +1,4 @@
-{ fetchurl, stdenv, gettext }:
+{ fetchurl, stdenv, gettext, glibc }:
 
 stdenv.mkDerivation rec {
   name = "libelf-0.8.13";
@@ -9,6 +9,11 @@ stdenv.mkDerivation rec {
   };
 
   doCheck = true;
+  
+  # For cross-compiling, native glibc is needed for the "gencat" program.
+  crossAttrs = {
+    nativeBuildInputs = [ glibc ];
+  };
 
   # Libelf's custom NLS macros fail to determine the catalog file extension on
   # Darwin, so disable NLS for now.