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/applications/misc/hello/default.nix

@@ -17,7 +17,7 @@ stdenv.mkDerivation rec {
       GNU Hello is a program that prints "Hello, world!" when you run it.
       It is fully customizable.
     '';
-    homepage = http://www.gnu.org/software/hello/manual/;
+    homepage = https://www.gnu.org/software/hello/manual/;
     license = licenses.gpl3Plus;
     maintainers = [ maintainers.eelco ];
     platforms = platforms.all;