Prefer cppu::UnoType<T>::get() to ::getCppuType((T*)0)

There's still a case with const sal_uInt16 which couldn't be converted
See http://nabble.documentfoundation.org/Questions-about-getCppuType-td4106361.html for more details

Change-Id: Iddc31168dba88d3ca0454fc76d31cda5f70eb5d1