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/tools/misc/parallel/default.nix

@@ -37,7 +37,7 @@ stdenv.mkDerivation rec {
          it possible to use output from GNU Parallel as input for other
          programs.
       '';
-    homepage = http://www.gnu.org/software/parallel/;
+    homepage = https://www.gnu.org/software/parallel/;
     license = licenses.gpl3Plus;
     platforms = platforms.all;
     maintainers = with maintainers; [ pSub vrthra ];