In file included from ../../../../dev/ic/ath.c:113: ../../../../dev/ic/athvar.h:52:42: ../contrib/sys/dev/ic/athhal.h: No such file or directory
This is not related to including IPsec code ("options IPSEC").
It seems that you do not have a complete source tree. You need
src/contrib/sys as well as sys/.
--
Greg Troxel <gdt@ir.bbn.com>