copyright (cherry picked from commit e3d74bdd7faca1583cc4dbea56bbe04a44db9e47)
4401. [bug] Fix leaks in contrib DLZ code. [RT #42707]
[master] fix null deref in some DLZ modules 3691. [contrib] Address null pointer dereference in LDAP and MySQL DLZ modules.
[master] mysql DLZ module 3569. [contrib] Ported mysql DLZ driver to dynamically-loadable module, and added multithread support. [RT #33394]