editline: enable sigstop

SIGSTOP is send when a user presses CTRL-Z.
It will send the application to the background.
Without this option, ctrl-z will be ignored.
With this option, it's possible to suspend
editline-based applications such as Nix.

pkgs/development/libraries/editline/default.nix

@@ -26,6 +26,8 @@ stdenv.mkDerivation rec {
     })
   ];
 
+  configureFlags = [ (lib.enableFeature true "sigstop") ];
+
   nativeBuildInputs = [ autoreconfHook ];
 
   outputs = [ "out" "dev" "man" "doc" ];