making the xar utility use expat instead of libxml2

Question

From the xar utilities source code, it looks like it can use either the expat or libxml2 XML parsers

#if HAVE_LIBXML_XMLREADER_H 
#include <libxml/xmlreader.h> 
#elif HAVE_BSDXML_H 
#include <bsdxml.h> 
#elif HAVE_EXPAT_H 
#include <expat.h>

How do I get it to use expat instead of libxml when I install it using ports?

Answer 1

The current version (1.5.2 as of this writing) requires libxml.

The word expat doesn't even occur in the source code.