[Differential] [Accepted] D5853: dhclient: Log a warning instead of bailing upon "illegal" options

[jhb (John Baldwin)]

jhb accepted this revision.

REVISION DETAIL
  https://reviews.freebsd.org/D5853

EMAIL PREFERENCES
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To: sepherosa_gmail.com, network, secteam, delphij, glebius, adrian, honzhan_microsoft.com, howard0su_gmail.com, decui_microsoft.com, freebsd-net-list, pkelsey, gnn, jhb
Cc: sbruno