Fix logging of errors creating the httpd.pid file.

perror() was converted to ap_log_error(), which will interpret the
specified APR error code properly.

The existing ap_log_error() call was changed so that the message is
formatted properly.  Note that this call is made from the mpm after
we detach from the foreground process, so it can only appear in the
log.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@85551 13f79535-47bb-0310-9956-ffa450edef68