(ITS#7761) Issue with modifying loglevel during long search operation

[mwarren@symas.com]

Full_Name: Mark Warren
Version: 2.4.38
OS: RHEL 5 x86-64
URL: ftp://ftp.openldap.org/incoming/
Submission from: (NULL) (199.190.53.83)


There is an issue where OpenLDAP will stop sending search results and fail to
update a dynamic config when the loglevel is modified during a long search
operation. 

Symptoms:
* No further search results sent to client although internally the operation
continues.
* Log level change does not take effect

Cause(Via Howard):
* send_search_entry() correctly returns an error because back-config wants a
pause
* back-bdb/back-hdb ignores this error
* The entry it tried to send doesn't get sent, and it just loops back to fetch
the next entry instead of quitting

Steps to reproduce:
1. Create large sample database. 2 million entries was more than sufficient
locally. 
2. Issue a search request for all entries.
3. Submit a modify request on olcLogLevel within cn=config while the above
search is still in progress.

Notes(Also via Howard):
* This is not a total hang as everything should resume after the internal search
operation finishes. 


Regards,
Mark Warren