Have you installed the developer version of libffi (i.e. the headers)?
If you've built it from source, have insured that the installation path
is in /etc/ld.so.conf and have you run ldconfig?
What does config.log
say? (look for 'checking ffi.h usability')
What is the output of 'make messages=yes'
In Slackware there's really no development version of anything! It's the whole package with headers and all, and libffi is included in the gcc package.
I did when installating the packages, but can't remember if I did or not when building the libraries again. What exactly is the path? I inserted /usr/GNUstep/System/Library/Libraries in ld.so.conf!
I'm not at home right now, so I can't say exactly what's in
config.log, but the usability tests for ffi.h and callback.h never pass! It's really strange since ffi.h is in /usr/include and libffi.so is in /usr/lib (those are also the directories I pass to ./configure).
I'll have to run make messages=yes when I get home later today...
Stefan