[1/N] Don't use CUDA.cmake module (#157188)

Small changes before removing CUDA.cmake.

Pull Request resolved: https://github.com/pytorch/pytorch/pull/157188
Approved by: https://github.com/ezyang

cmake/Modules/FindCUB.cmake

@@ -3,7 +3,7 @@
 #  CUB_INCLUDE_DIRS - the CUB include directory
 
 find_path(CUB_INCLUDE_DIR
-        HINTS "${CUDA_TOOLKIT_INCLUDE}"
+        HINTS "${CUDAToolkit_INCLUDE_DIRS}"
         NAMES cub/cub.cuh
         DOC "The directory where CUB includes reside"
 )

torch/CMakeLists.txt

@@ -478,6 +478,11 @@ else()
   set(TORCH_VERSION_DEBUG 0)
 endif()
 
+set(CUDA_VERSION "")
+if(CUDAToolkit_VERSION_MAJOR)
+  set(CUDA_VERSION "${CUDAToolkit_VERSION_MAJOR}.${CUDAToolkit_VERSION_MINOR}")
+endif()
+
 add_custom_target(
   gen_torch_version ALL
   "${Python_EXECUTABLE}" "${TOOLS_PATH}/generate_torch_version.py"