BUG: Fix MacOS style library fix up

Following r22235, slicer couldn't start on Mac due to the style. In the
libraries fixup, the styles plugins weren't properly bundled.
Adding the style library fixes that.

Fixes #3253

git-svn-id: http://svn.slicer.org/Slicer4/trunk@22238 3bd1e089-480b-0410-8dfb-8563597acbee