This is a shared library designed to give FontForge (and others) access to
Raph Levien's spiro splines.
You may (possibly) be able to obtain more recent versions of Spiro from
http://levien.com/garden/ppedit/
use the get-spiro-src.sh script to do so.
To build, type
./configure
make
make install
Currently I extract very little from spiro, just the bare minimum to convert
a series of (marked) points to a set of cubic bezier curves which ff can use.