Fixed compile of lupdate.

lupdate wants to use private QtDeclarative symbols.
Either the symbols need to be made public, or lupdate needs to compile
its own copy of the code.

This commit applies the latter approach.

Change-Id: I119c2d044fe2a8953867f7b6e2fc446dee65cce3
Reviewed-on: http://codereview.qt-project.org/5181


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Toby Tomkins <toby.tomkins@nokia.com>