Make Nixpkgs jobs unique

That is, there are now distinct jobs like ‘coreutils.x86_64-linux’ and
‘coreutils.x86_64-darwin’, rather than a single job ‘coreutils’ with
multiple builds.  This means that testing a job is simpler:

  $ nix-build pkgs/top-level/release.nix -A coreutils.x86_64-linux

See https://github.com/NixOS/hydra/issues/60 for the motivation.

pkgs/development/libraries/aterm/2.5.nix

@@ -16,14 +16,15 @@ stdenv.mkDerivation {
     # SIZEOF_LONG, SIZEOF_INT and SIZEOF_VOID_P being set.
     ./sizeof.patch
   ];
-  
+
   doCheck = true;
 
-  dontDisableStatic = true; 
+  dontDisableStatic = true;
 
   meta = {
     homepage = http://www.cwi.nl/htbin/sen1/twiki/bin/view/SEN1/ATerm;
     license = "LGPL";
     description = "Library for manipulation of term data structures in C";
+    platforms = stdenv.lib.platforms.all;
   };
 }