This submission was done by hand-applying FreeBSD local modifications on
top of the UCB code, rather than trying to patch the UCB code in on top
of the FreeBSD code due to the extensive changes.
Reviewed by: pst (been handling 30k routes for 4+ months)
Obtained from: Sklower/Woody/Honing/Traina (8.4 UCB release)
Declare a complete prototype for the function pointer *ifa_rtrequest.
radix.h:
Declare a complete prototype for the function pointer *rnh_walktree
and for the function rn_walktree.
Uniformize idempotency ifdef.