all the other bt_XXX() functions in i386/scsi/bt*.
This the important effect of forcing a link error if the user is
still using the old "vector btintr" which is dangerously wrong
after Justin's updates to the driver.
The correct isa vector line for the bt driver is "vector bt_isa_intr".
Justin mentioned this in the commit message and updated LINT and
GENERIC. This change is to enforce that.. :-)
