Mainly meant to deal with the IRIX case which seems to requrie a "-lgen" lib
to find the basename function and thus without the gen lib, it finds the
header but not the function and our replacement function has a prototype
that doesn't match the IRIX one.
A different approach would be to make configure detect and use -lgen for the
systems that require it.
#include <stdarg.h>
#include <time.h>
#include <sys/stat.h>
-#ifdef HAVE_LIBGEN_H
+#if defined(HAVE_LIBGEN_H) && defined(HAVE_BASENAME)
#include <libgen.h>
#endif
#include "formdata.h"