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/gnutls/generic.nix

@@ -82,7 +82,7 @@ stdenv.mkDerivation {
        tampering, or message forgery."
     '';
 
-    homepage = http://www.gnu.org/software/gnutls/;
+    homepage = https://www.gnu.org/software/gnutls/;
     license = licenses.lgpl21Plus;
     maintainers = with maintainers; [ eelco wkennington fpletz ];
     platforms = platforms.all;