Ticket 47499 - if nsslapd-cachememsize set to the number larger than
the RAM available, should result in proper error message.
Bug Description: The server allows any value to be set for all the cache sizes. If
this value is too large it will basically crash the server.
Fix Description: Do a value verification before allowing the change. Report an
error 53 and a descriptive error string if the value is too large.
Reviewed by: nhosoi(Thanks!!)