Switch from tmpnam() to apr_file_mktemp() so that gcc with a recent glibc

will shut the hell up about tmpnam() being unsafe.  htpasswd.c needs a
similar treatment, but it won't be _quite_ as easy since htpasswd has not
been completely apr-ized yet.


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@91222 13f79535-47bb-0310-9956-ffa450edef68