I think that the sup tree of -current is missing a header file update.
===> sbin/ipfw
cc -O2 -c /pub/.0/FreeBSD/FreeBSD-current/src/sbin/ipfw/ipfw.c
/pub/.0/FreeBSD/FreeBSD-current/src/sbin/ipfw/ipfw.c: In function `show_ipfw':
/pub/.0/FreeBSD/FreeBSD-current/src/sbin/ipfw/ipfw.c:184: structure has no membe
r named `fw_bcnt'