Sadly Jim Ablett has decided to stop his excellent work with compiling various chess engines. This of course includes Mediocre.
I've never spent much time generating native exceutables of Mediocre and I'm quite sure I won't start now. Mediocre is a Java engine after all, and should probably be run as a Java application.
I'm quite aware of the limitations on some UIs (like Chessbase, atleast in the past), but I still see it as a limitation on their side and not mine.
Feel free to ask if you need help getting Mediocre to run as a Java application in whatever UI you use, I'm still around and answering questions. :)