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/compilers/clean/default.nix

@@ -14,8 +14,7 @@ stdenv.mkDerivation rec {
     })
     else throw "Architecture not supported";
 
-  hardening_format = false;
-  hardening_pic = false;
+  hardeningDisable = [ "format" "pic" ];
 
   # clm uses timestamps of dcl, icl, abc and o files to decide what must be rebuild
   # and for chroot builds all of the library files will have equal timestamps.  This