Use general hardening flag toggle lists

The following parameters are now available:

  * hardeningDisable
    To disable specific hardening flags
  * hardeningEnable
    To enable specific hardening flags

Only the cc-wrapper supports this right now, but these may be reused by
other wrappers, builders or setup hooks.

cc-wrapper supports the following flags:

  * fortify
  * stackprotector
  * pie (disabled by default)
  * pic
  * strictoverflow
  * format
  * relro
  * bindnow

pkgs/applications/science/geometry/drgeo/default.nix

@@ -5,7 +5,7 @@ stdenv.mkDerivation rec {
   name = "drgeo-${version}";
   version = "1.1.0";
 
-  hardening_format = false;
+  hardeningDisable = [ "format" ];
 
   src = fetchurl {
     url = "mirror://sourceforge/ofset/${name}.tar.gz";