Patch: 'ldapmodify -c' should return error on failure (ITS#2133)

Patch: 'ldapmodify -c' should return error on failure  (ITS#2133)

Written by Hallvard B. Furuseth and placed into the public domain.
This software is not subject to any license of the University of Oslo.

'ldapmodify -c' returned the error status from the _last_ LDIF entry,
so a bad entry followed by a good entry returns success.
This patch makes it return the status of the last _failed_ entry,
or 0 if all entries succeeded.