This fnlib package has now been adapted to use automake and autoconf.
This means that you will need the usual GNU tools to build these in
maintainer mode from the CVS tree.  You can basically type

aclocal
automake --add-missing
autoconf
./configure
make

This library requires Imlib to be installed and working properly (it must
handle tiff, gif, png and xpm formats with native transparency).

.