in if_addgroup(), call the new pfi_group_addmember() instead of

in if_addgroup(), call the new pfi_group_addmember() instead of
pf_group_change() - the latter is called by _addmemeber now to update dynaddr.
before this, "set skip on lo", ifconfig lo1 create -> no skip on lo1 until
pf rueset got reloaded. Now lo1 gets the skip flag as intended. This has
caused much confusion with i. e. gif interfaces in the past.
ok benno, very excited ok phessler