Created attachment 34134 [details]
Add log message when apr_thread_mutex_create fails

Function apr_thread_mutex_create may fail. The majority of calls have checked the return value and printed log message like the following code snippet, while the others have not. Those unchecked ones probably need logs too (see attachment).

/* httpd-2.4.10/modules/database/mod_dbd.c:689:15 */
        rv2 = apr_thread_mutex_create(&group->mutex,
                                      APR_THREAD_MUTEX_DEFAULT, pool);
        if (rv2 != APR_SUCCESS) {
             ap_log_error(APLOG_MARK, APLOG_CRIT, rv2, s, APLOGNO(00635)
                          "Failed to create thread mutex");
             return rv2;
        }