(ITS#3865) Passing a directory to slapd with "-f" is equivalent to reading an empty file

[ando@sys-net.it]

Full_Name: Pierangelo Masarati
Version: HEAD (might affect released versions)
OS: Linux (may be irrelevant)
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (131.175.154.56)
Submitted by: ando


When erroneously passing a(n existing) directory as arg to the "-f" switch of
slapd, it silently opens it and gives up with no error, much like it werre
passed an empty file.  This may not be the intended behavior; I suggest an error
is returned.

p.