(ITS#4782) back-ldap bugs

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: HEAD
OS: 
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (76.168.84.21)
Submitted by: hyc


1) back-ldap fails to startup if back-monitor isn't enabled. It should silently
skip usage of back-monitor, the way back-bdb does.

2) multiple calls are made to ldap_back_is_proxy_authz with
sendok=LDAP_BACK_SENDERR without checking the return status or aborting the
operation. As such, when proxy authorization is not in effect for an operation,
the client receives multiple Error Result messages for its request (even though
it continues to completion). Likewise for ldap_back_proxy_authz_bind. Either
these functions should never send a result back to the client, or their return
status should be checked and processing should stop when they fail. I've cleaned
up several instances of this type of error in previous revisions but can't track
them all down now. Errors of this type may also exist in RE23; I haven't
looked.