winbindd: make a copy of xid's in wb_xids2sids_send()

winbindd: make a copy of xid's in wb_xids2sids_send()

This is in preparation of setting the result of the mapping in the top-
level callback wb_xids2sids_done(), not in the per-idmap-domain callback
wb_xids2sids_dom_done().

When caching the mapping we need the id-type from the backend, so we
need a way to pass up that information from wb_xids2sids_dom_done() up
to wb_xids2sids_done()

The xids array copy gets passed from wb_xids2sids_send() to
wb_xids2sids_dom_send(), so wb_xids2sids_dom_done() can then directly
update the top-level copy.

Bug: https://bugzilla.samba.org/show_bug.cgi?id=13802

Signed-off-by: Ralph Boehme <slow@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>