Bug Description:  When concurrently updating multiple backends the
                  memberOf and retrocl plugins can deadlock on each
                  other.  This is caused by the required retrocl lock,
                  and the db lock on the changenumber index in the
                  retrocl db.

Fix Description:  Added scoping to the retrocl that allows subtrees/suffixes
                  to be included or excluded.  Also moved the existing
                  memberOf scoping outside of its global lock.

                  Also improved the memberOf config copying to be consistent
                  and more efficient.  Improved the memberOf scoping attributes
                  to be multivalued.  And, properly valdiated new config
                  settings in the preop valdiation function, instead of the
                  "apply config" function.

https://fedorahosted.org/389/ticket/47931

Valgrind: passed

Reviewed by: nhosoi(Thanks!)

(cherry picked from commit fd959ac864d6d86d24928bc2c6f097d1a6031ecd)
(cherry picked from commit d8108476d3bedbcc03f6c61bfb3d50e921faaf42)