(ITS#5784) [enhancement] add support for "What Failed?" LDAP control

[ando@sys-net.it]

Full_Name: Pierangelo Masarati
Version: HEAD
OS: irrelevant
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (82.63.140.131)
Submitted by: ando


I'm about to add support for what I termed the "What Failed?" LDAP control,
which allows to request detailed information about what extension caused the
failure of a request.  The commit includes a preliminary version of what I
intend to submit as an I.D. shortly.

p.