Revert "Tests: Use @rpath only on OS X 10.6 and greater"

This reverts commit 741395f103d868ef9f7d1c2ac552c5eefcf729cc.
Merge topic 'rpath-osx-10_6' into next

e9ca4370 Revert "Tests: Use @rpath only on OS X 10.6 and greater"