[QBS] unset _UNICODE and UNICODE defines

[Kurt Keller]

Hello List,

I am testing qbs as a build system for our application development.

I am preparing the port of our applications towards Qt 5.1.1 (from Qt
4.8.5) and have the problem for some very old applications to unset the
compiler flags /D_UNICODE and /DUNICODE on windows.

There is the (undocumented) property "windowsApiCharacterSet" in the cpp
module. Setting this to 'none' in my project file unsets the unwanted
#defines only when there is no dependency to the Qt core module.

Setting windowsApiCharacterSet: "none" directly in the module source file
(share/modules/cpp/windows-msvc.qbs) works, but I do not want to change qbs
internals.

Is there another way to prevent qbs from setting these /D compiler flags? 

-- 
Kurt