#96 AM_PATH_XML2 macro is no longer supported

[Sebastian Freundt]

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but even that seems outdated, as since about 2008 libxml2 ships with a pkgconfig file.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:
PKG_CHECK_MODULES([XML2], [libxml-2.0])
or some such.