ctdb-ipalloc: ctdb_takeover_run_core() takes ipalloc_state

ctdb-ipalloc: ctdb_takeover_run_core() takes ipalloc_state

As do the functions called below it.  They no longer need a CTDB
context.

create_merged_ip_list() now takes both a CTDB context and an
ipalloc_state.

Drop ipalloc_state from CTDB context.  So the substitution in the
code is:

  ctdb->ipalloc_state  ->  ipalloc_state

Tweak the test code to match.

Signed-off-by: Martin Schwenke <martin@meltin.net>
Reviewed-by: Amitay Isaacs <amitay@gmail.com>