strerror() as strerror() may not be thread safe.  Likely should
be used by SLAPD.

And some code cleanup.

Also, as written, the code will behave better in the face of unsolicited
noticifications (such as notice of disconnect).  However, code needs to
be improved to better distinguished such from expected result response.
Delete improvements are limited to base object delete.  Should be applied
to -p[rune] option as well.