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/libcdio/default.nix

@@ -26,7 +26,7 @@ stdenv.mkDerivation rec {
       ISO-9660 filesystems (libiso9660), as well as utility
       programs such as an audio CD player and an extractor.
     '';
-    homepage = http://www.gnu.org/software/libcdio/;
+    homepage = https://www.gnu.org/software/libcdio/;
     license = licenses.gpl2Plus;
     platforms = platforms.linux ++ platforms.darwin;
   };