NVIDIA CUDA Toolkit version whose Visual Studio toolset to use.

The Visual Studio Generators for VS 2010 and above support using a CUDA toolset provided by a CUDA Toolkit. The toolset version number may be specified by a field in CMAKE_GENERATOR_TOOLSET of the form cuda=8.0. If none is specified CMake will choose a default version. CMake provides the selected CUDA toolset version in this variable. The value may be empty if no CUDA Toolkit with Visual Studio integration is installed.