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/development/libraries/java/swt/default.nix

@@ -28,7 +28,7 @@ in stdenv.mkDerivation rec {
 
   builder = ./builder.sh;
 
-  hardening_format = false;
+  hardeningDisable = [ "format" ];
 
   # Alas, the Eclipse Project apparently doesn't produce source-only
   # releases of SWT.  So we just grab a binary release and extract