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slackware 3.1 appears to have a missing libdl symlink, and also
misses the /usr/include/dlfcn.h include file.
Solution(s):
    - get ld.so-1.7.14 (or newer) from your favority linux archive
      it contains ld.so-1.7.14/d-link/libdl/dlfcn.h, and copy this
      file to /usr/include

    - set the symlink if you have not fully installed a new version
      from the above updated ld.so

        cd /lib
        ln -s libdl.so.1.7.14 libdl.so

      (or whichever your most recent version winds up to be)