* gnu/gnunet/config.scm.in: New file.
* gnu/gnunet/common.scm: Use (gnu gnunet config).
(gnunet-util-ffi, gnunet-fs-ffi, gnunet-identity-ffi): Use the new
%libgnunet-util etc. variables.
* configure.ac: Substitute GNUNETUTIL_LIBDIR, GNUNETFS_LIBDIR, and
GNUNETIDENTITY_LIBDIR.
* Makefile.am (GOBJECTS): Add gnu/gnunet/config.go.