Merge topic 'cuda-clang'

a653ca95 Tests: Update CUDA tests to work with Clang
5df21adf CUDA: Add support for Clang compiler
dc2eae1f FindCUDAToolkit: Factor out discovery code into a separate file
70be10cb CUDA: Remove toolkit include dirs from implicit include dirs only with NVIDIA

Acked-by: Kitware Robot <kwrobot@kitware.com>
Acked-by: Artem Belevich <tra@google.com>
Acked-by: Robert Maynard <robert.maynard@kitware.com>
Acked-by: Axel Huebl <axel.huebl@plasma.ninja>
Acked-by: friendnick <ikoval67@gmail.com>
Acked-by: Patrik Huber <patrikhuber@gmail.com>
Merge-request: !4442