(ITS#3551) back-sql sends search result multiple times

[hyc@OpenLDAP.org]

Full_Name: Howard Chu
Version: HEAD/2.3
OS: Linux
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (24.126.120.178)
Submitted by: hyc


In looking at back-sql/search.c to examine its response to an abandon, I see
that a couple of error conditions (including TIMELIMIT_EXCEEDED) send a result
immediately, then goto end_of_search which also calls send_ldap_result, so
redundant results are sent.

This was while reviewing to check that all backends consistently return
SLAPD_ABANDON in response to an Abandon request.