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/libpng/default.nix

@@ -3,11 +3,11 @@
 assert zlib != null;
 
 let
-  version = "1.6.13";
-  sha256 = "09g631h1f1xvrdiy36mh1034r9w46damp9jcg7nm507wlmacxj6r";
+  version = "1.6.16";
+  sha256 = "0q5ygy15jkpqbj5701ywrjzqp4nl5yz3r4g58h2p0kiycggm9xs2";
   patch_src = fetchurl {
     url = "mirror://sourceforge/libpng-apng/libpng-${version}-apng.patch.gz";
-    sha256 = "017pnxp3zhhlh6mg2yqn5xrb6dcxc5p3dp1kr46p8xx052i0hzqb";
+    sha256 = "1sf27a5gvwvcm4wsf2pyq87d3g4l2fym8cirq9sli54bi753ikbh";
   };
   whenPatched = stdenv.lib.optionalString apngSupport;
 
@@ -35,8 +35,8 @@ in stdenv.mkDerivation rec {
   meta = with stdenv.lib; {
     description = "The official reference implementation for the PNG file format" + whenPatched " with animation patch";
     homepage = http://www.libpng.org/pub/png/libpng.html;
-    license = "free-non-copyleft"; # http://www.libpng.org/pub/png/src/libpng-LICENSE.txt
+    license = licenses.libpng;
     platforms = platforms.all;
-    maintainers = [ maintainers.vcunat ];
+    maintainers = [ maintainers.vcunat maintainers.fuuzetsu ];
   };
 }