If you don't have all your m4 files installed in a common directory
and your aclocal is not set up to scan all the different m4 directories,
the autogen.sh script might fail with something like this:

+ aclocal 
aclocal: configure.in: 12: macro `AM_PROG_LIBTOOL' not found in library
aclocal: configure.in: 551: macro `AM_PATH_XML2' not found in library

To fix this you will have to enter the lines that are in the autogen.sh script
manually, changing the aclocal line to include the necessary directories.

aclocal -I <libtool m4 dir> -I <xml m4 dir "xml2-config --prefix"/share/aclocal>

example:
aclocal -I /usr/.../libtool-1.5/share/aclocal -I /usr/.../libxml2-2.6.2/share/aclocal

