These RXTX files were just copied directly from the rxtx website http://rxtx.qbang.org/wiki/index.php/Download

Their versions are reported as:
 Native lib Version = RXTX 2.1-7r2
 Java lib Version   = RXTX 2.1-7r2




If you've never used RXTX before on your Mac OS X box, run the command:

% ./macosx_setup.command

And then shutdown (not just log out) and log back in again.
And read this faq from Processing: http://processing.org/faq/bugs.html#serial