Calling in{6,}_purgeaddr() is not enough to remove an address from

Calling in{6,}_purgeaddr() is not enough to remove an address from
an interface.  Two other operations are performed when issuing a
SIOCDIFADDR{_IN6,} ioctl: call the address hook and the per-driver
ioctl function.

Since carp(4) relies on an address hook to recalculate its hash, make
sure to call this hook when IFXF_NOINET6 is set or when the rdomain is
changed.

ok henning@, mikeb@