dbwrap_rbt: add nested traverse protection
Multiple dbwrap_traverse_read() calls are possible.
store() and delete() on a fetch locked record
are rejected during dbwrap_traverse_read().
A dbwrap_traverse() within a dbwrap_traverse_read()
behaves like a dbwrap_traverse_read().
Nested dbwrap_traverse() calls are not possible.
BUG: https://bugzilla.samba.org/show_bug.cgi?id=11375
BUG: https://bugzilla.samba.org/show_bug.cgi?id=11394
Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Volker Lendecke <vl@samba.org>
(cherry picked from commit
590507951fc514a679f44b8bfdd03c721189c3fa)