Don't realpath jars on the classpath.
Review Request #1588 - Created Jan. 9, 2015 and submitted
We use a symlink farm so that paths inside zinc analysis files will be portable. The realpath-ing caused zinc analysis to contain direct references into the ivy cache, which is obviously not portable.
CI baking: https://travis-ci.org/pantsbuild/pants/builds/46501760
TODO: Add a regression test. Putting this out there now to unblock folks.