Ticket 20 - Allow automember to work on entries that have already been added
Bug Description: If the server can not open a ldif for reading(mapping task), an
incorrect error and file name is returned.
Fix Description: Report the correct file name, and correctly grab the OS error/string.
Also made slapd_pr_strerr() and slapd_system_strerr() public, so I
refactored the function names to be "slapi_" - so a lot of files are
touched but the main change for this ticket is still in automember.c
Reviewed by: richm(Thanks)