Ticket #48339 - Share nsslapd-threadnumber in the case nunc-stans is enabled, as well.
Description: When nunc-stans is enabled, instead of getting the
thread number from the environment variable MAX_THREADS, use the
value of config parameter nsslapd-threadnumber.
https://fedorahosted.org/389/ticket/48339
Reviewed by rmeggins@redhat.com (Thank you, Rich!!)
(cherry picked from commit ab8ed9a5ebb0d15b55d7525ed1d5dbeebd8c7563)