[CMake] FindQt4.cmake to automatically include QT_USE_FILE?

[John Drescher]

> If you don't care for the macros and want to set up the
> include-directories and defines yourself, no. Also, it is common to
> find_package(Qt4) in the top-level CMakeLists.txt file, but then include
> QT_USE_FILE only in specific subdirectories, where Qt is actually used.
>

I have started doing that in my projects. It cuts down on the
unnecessary includes for subprojects that do not need Qt.

John