run all hooks in a list
hook_desc_head *head, int
function invokes all hooks established using the
hook_establish(9) function. Hooks are called in the order of the
TAILQ that head points to, however
hook_establish(9) can put the hooks either at the head or the tail of
that queue, making it possible to call the hooks either in the order of
establishment, or its reverse.
The flags can specify
remove already processed hooks from the hook list and
HOOK_FREE to also free them. In most cases either no
flags should be used or
HOOK_FREE at the same time, since just HOOK_REMOVE
will drop the only reference to allocated memory and should only be used in
situations where freeing memory would be illegal and unnecessary.
This function is used to implement the dostartuphooks(9) macro.