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/gettext/default.nix

@@ -12,9 +12,8 @@ stdenv.mkDerivation rec {
 
   outputs = [ "out" "doc" ];
 
-  # FIXME needs gcc 4.9 in bootstrap tools
-  hardening_stackprotector = false;
-  hardening_format = false;
+  # FIXME stackprotector needs gcc 4.9 in bootstrap tools
+  hardeningDisable = [ "format" "stackprotector" ];
 
   LDFLAGS = if stdenv.isSunOS then "-lm -lmd -lmp -luutil -lnvpair -lnsl -lidmap -lavl -lsec" else "";