Ever since rev 1.68 re(4) checks the validity of link in re_start.
But rlphy(4) got a garbled data due to a different bit layout used on
8139C+ and it couldn't report correct link state. To fix it, ignore
BMCR_LOOP and BMCR_ISO bits which have different meanings on 8139C+.
I think this also make dhclient(8) work on 8139C+.
Reported by: Gerrit Kuehn <gerrit AT pmp DOT uni-hannover DOT de>
Tested by: Gerrit Kuehn <gerrit AT pmp DOT uni-hannover DOT de>