On windows when you run `nvcc -v` all the env variables will
be printed before nvcc verbose output. This allows us to handle
the cases where env variable exists with the same name as a magic
nvcc keyword we parse
Upcoming versions of nvcc are adding support for `SYSTEM_INCLUDES`
which contain includes that are implicitly used with `-isystem`
instead of `-I`.
Support of this is needed in CMake as some CUDA Toolkit releases will
start to have a different include directory layout and using only the
output from `INCLUDES` will be insufficient to find all headers.
