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/tools/filesystems/udftools/default.nix

@@ -11,7 +11,8 @@ stdenv.mkDerivation rec {
   buildInputs = [ ncurses readline ];
 
   patches = [ ./gcc5.patch ];
-  hardening_fortify = false;
+
+  hardeningDisable = [ "fortify" ];
 
   preConfigure = ''
     sed -e '1i#include <limits.h>' -i cdrwtool/cdrwtool.c -i pktsetup/pktsetup.c