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/shells/bash/4.4.nix

@@ -106,7 +106,7 @@ stdenv.mkDerivation rec {
     '';
 
   meta = with stdenv.lib; {
-    homepage = http://www.gnu.org/software/bash/;
+    homepage = https://www.gnu.org/software/bash/;
     description =
       "GNU Bourne-Again Shell, the de facto standard shell on Linux" +
         (if interactive then " (for interactive use)" else "");

pkgs/shells/rush/default.nix

@@ -31,7 +31,7 @@ stdenv.mkDerivation rec {
          sftp-server or scp, that lack this ability.
       '';
 
-    homepage = http://www.gnu.org/software/rush/;
+    homepage = https://www.gnu.org/software/rush/;
     license = stdenv.lib.licenses.gpl3Plus;
 
     maintainers = [ stdenv.lib.maintainers.bjg ];