to simplify changes elsehere.
Add dependency on new file netipec/ipsec_netbsd.c, for some NetBSD-specific
required functionality (e.g., differences in ctl-input keydb handling).
code is derived from Sam Leffler's FreeBSD port of OCF, which is in
turn a port of Angelos Keromytis's OpenBSD work.
Credit to Sam and Angelos, any blame for the NetBSD port to me.