vim: Disable hardening flag fortify

Fortify hardening detects a probable buffer overflow in vim at runtime. This
has to be fixed upstream.

Debian also disables fortify:

  https://anonscm.debian.org/cgit/pkg-vim/vim.git/tree/debian/rules#n6

pkgs/applications/editors/vim/default.nix

@@ -30,6 +30,8 @@ stdenv.mkDerivation rec {
     "--enable-nls"
   ];
 
+  hardeningDisable = [ "fortify" ];
+
   postInstall = ''
     ln -s $out/bin/vim $out/bin/vi
     mkdir -p $out/share/vim