First, build the ffcall package. For full details, see the README files in the
ffcall subdirectory. The basic process on Unix is

    cd ffcall
    ./configure
    make
    make check

and on Windows it is

    cd ffcall
    nmake -f Makefile.msvc

For platforms supported by the ffcall package, see ffcall/PLATFORMS

Now, build the FFI package in the usual manner.

   perl Makefile.PL
   make
   make test
   make install

See the pod documentation for details of usage.

Note that the test suite needs some work, to standardise it. Also, there are a
number of Win32-specific tests which should be extracted into a separate
file...