`QT_QMAKE_EXECUTABLE` is not set, making `projects/win32/qt5.package.cmake` unusable

Whith the following:

USE_SYSTEM_QT
PACKAGE_SYSTEM_QT

One would expect projects/win32/qt5.package.cmake code to be used, but it looks like it is not. This may be Qt4 legacy code.

ParaView does not rely on it for packaging but rely on fixup_bundle.windows.py for packaging the dlls.

Maybe projects/win32/qt5.package.cmake should be removed.