Some newer versions of gcc (observed with a patched gcc 4.5.1) seem to
treat our offsetof() implementation as not being a compile-time
constant. Fix by using __builtin_offsetof() when available. (As with
the original offsetof() macro, this code is copied from the Linux
kernel's stddef.h.)
Reported-by: Arkadiusz Miskiewicz <arekm@maven.pl>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
Michael Brown