Merge staging into closure-size

The most complex problems were from dealing with switches reverted in
the meantime (gcc5, gmp6, ncurses6).
It's likely that darwin is (still) broken nontrivially.

pkgs/development/libraries/gdk-pixbuf/default.nix

@@ -3,14 +3,14 @@
 
 let
   ver_maj = "2.32";
-  ver_min = "0";
+  ver_min = "1";
 in
 stdenv.mkDerivation rec {
   name = "gdk-pixbuf-${ver_maj}.${ver_min}";
 
   src = fetchurl {
     url = "mirror://gnome/sources/gdk-pixbuf/${ver_maj}/${name}.tar.xz";
-    sha256 = "0rqvj5gcs2zfyyg9llm289b0xkj4mrhzxfjpjja0wx1m6vn5axjk";
+    sha256 = "1g7kjxv67jcdasi14n7jan4icrnnppd1m99wrdmpv32k4m7vfcj4";
   };
 
   outputs = [ "dev" "out" "docdev" ];
@@ -27,6 +27,11 @@ stdenv.mkDerivation rec {
 
   propagatedBuildInputs = [ glib libtiff libjpeg libpng jasper ];
 
+  # on darwin, tests don't link
+  preBuild = stdenv.lib.optionalString (stdenv.isDarwin && !doCheck) ''
+    substituteInPlace Makefile --replace "docs tests" "docs"
+  '';
+
   configureFlags = "--with-libjasper --with-x11"
     + stdenv.lib.optionalString (gobjectIntrospection != null) " --enable-introspection=yes"
     ;