trustedGrub: disable stackprotector/pic hardening

pkgs/tools/misc/grub/trusted.nix

···
   buildInputs = [ ncurses libusb freetype gettext devicemapper ]
     ++ optional doCheck qemu;
 
+  hardening_stackprotector = false;
+  hardening_pic = false;
+
   preConfigure =
     '' for i in "tests/util/"*.in
        do