configure.in:99 AM_PATH_XML2('2.0.0', , AC_MSG_ERROR(libxml2 must be installed.))
That macro has been deprecated in 2007 and is now no longer available.
The author back then recommended xml2-config (see e.g. http://xmlsoft.org/FAQ.html#Developer\)
but even that seems outdated, as since about 2008 libxml2 ships with a pkgconfig file.
Please change above line to:
or some such.