fix udp checksum verification if ip options are present; report from Pyun via dhartmei@; ok mcbride@, dhartmei@
fix udp checksum verification if ip options are present;
report from Pyun via dhartmei@; ok mcbride@, dhartmei@

orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars,orumin/openbsd-efivars