(synced syncprov.c with HEAD)

Segfault fix for ldapadding new schema entries

Various documentation updates
bconfig segfault w/ ldapadd on schema fix noted.

fix "require" inheritance and handling of "none" (ITS#4574)
Add access control note to authz-regexp discussion
ITS#4613 note that lastmod also controls entryCSN and entryUUID

Also: acl_match_set(): Initialize bvals before backend_attribute(,,,,&bvals,);