core: Avoid a compiler warning when NO_LINGCLOSE is used (-Wunreachable-code).

Also, check c->aborted before apr_socket_shutdown() because it is set earlier,
and there is no point in calling shutdown() before close().


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@1703248 13f79535-47bb-0310-9956-ffa450edef68