Call ap_log_error() instead of ap_log_rerror() from alloc_listener().

This bug, introduced in a recent commit, caused a segfault when the
hostname couldn't be resolved.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@87386 13f79535-47bb-0310-9956-ffa450edef68