bzero() siop_target structure after malloc().
bzero() siop_target structure after malloc().

In combination with previous openings fix makes Niklas happy. Probably
fixes some negotiation bugs too.

Another good candidate for -stable.

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