Cmake additional defines

If inside the CMake project there are some c++ defines added with ADD_DEFINITIONS (-D_LINUX for example), the C++ parser ignores them. If the project uses these defines to make some declarations, the entire project has problems with auto completion, since there surely will be compilation errors. The project of course will compile correctly when building it.

A workaround would be manually setting the additional defines for the C++ parser in the project options.