tools/ctdb: Factor, simplify and improve robustness of ipreallocate code

tools/ctdb: Factor, simplify and improve robustness of ipreallocate code

Having other functions call control_ipreallocate() suggests that the
it might look at the argv/argv arguments that are passed.  This is not
the case.  Change the callers so they call the new ipreallocate()
function instead.

Broadcast CTDB_SRVID_TAKEOVER_RUN to all connected nodes.  Inactive
nodes will ignore it.  This is safe since we only want 1 reply.  If we
didn't get a response, we don't actually care if there's no active
recovery master - just fire, wait, retry, ...

Ignore some failures on the basis that they might be transient, so it
is probably worth retrying.

Signed-off-by: Martin Schwenke <martin@meltin.net>