Treewide: use HTTPS on GNU domains

HTTP -> HTTPS for :
- http://gnu.org/
- http://www.gnu.org/
- http://elpa.gnu.org/
- http://lists.gnu.org/
- http://gcc.gnu.org/
- http://ftp.gnu.org/ (except in fetchurl mirrors)
- http://bugs.gnu.org/

pkgs/development/libraries/libiconv/default.nix

@@ -46,7 +46,7 @@ stdenv.mkDerivation rec {
       applications.
     '';
 
-    homepage = http://www.gnu.org/software/libiconv/;
+    homepage = https://www.gnu.org/software/libiconv/;
     license = lib.licenses.lgpl2Plus;
 
     maintainers = [ ];