Ticket 47759 - Crash in replication when server is under write load
Bug Description: When the server is under alot of load, a race condition allows
a replication connection LDAP struct to be freed(unbind) while
it is being used by another thread. This leads to a crash.
Fix Description: Extend the connection lock to also cover ldap client interaction
(e.g. conn->ld struct).
https://fedorahosted.org/389/ticket/47759
Reviewed by: nhosoi & rmeggins(Thanks!!)
(cherry picked from commit 9940ca29ca258891c52640a23adc2851afe59d0e)