title: Autoconf check for struct flock
body: <p><code>fcntl()</code> uses <code>struct flock</code> structure to define and check file locks. Unfortunately, on different Unix systems the fields in this structure are in different order. Does anybody know how one could check for it with autoconf or at least check if the structure is in specific format (e.g. the question would be - does the struct format matches the Linux format)? </p>