Ticket #47320 - put conn on work_q not poll list if conn has buffered more_data

Description: Additional change to
  commit ed88c40218c3fb8944618927e7865d74bc922c02
to fix the self-deadlock.
Replacing bind_credentials_set with bind_credentials_set_nolock
in handle_handshake_done.  The handle_handshake_done is only
called from connection_read_operation, where lock on c_mutex
is already obtained.  Thus, the replacement is safe.

https://fedorahosted.org/389/ticket/47320

ldap/servers/slapd/auth.c

@@ -539,7 +539,7 @@ handle_handshake_done (PRFileDesc *prfd, void* clientData)
 	 * Associate the new credentials with the connection.  Note that
 	 * clientDN and clientCert may be NULL.
 	 */
-	bind_credentials_set( conn, SLAPD_AUTH_SSL, clientDN,
+	bind_credentials_set_nolock( conn, SLAPD_AUTH_SSL, clientDN,
 			SLAPD_AUTH_SSL, clientDN, clientCert , NULL);
 done:
     slapi_ch_free_string(&subject);