Fixed compile of QtHelp on mac when frameworks are in use

Fixed compile of QtHelp on mac when frameworks are in use

Removed the incorrect assumption that QtCLucene is never a
framework.

Note that this logic still doesn't match exactly what is in qtAddLibrary
or qtAddModule in qt_functions.prf, therefore the build may still
fail in some exotic setups.

Change-Id: If032c0c4ac6031b5bb28033996a8773ecdb077e9
Reviewed-on: http://codereview.qt-project.org/5264
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Toby Tomkins <toby.tomkins@nokia.com>