OpenCL_INCLUDE_DIRS and OpenCL_LIBRARIES are not set.

Hello, I'm currently building and testing the OpenCL-SDK, and I have a question.

First, I built and installed the OpenCL-SDK using CMake. Then, in another CMake project, I called `find_package(OpenCL REQUIRED)` to use OpenCL.

The `OpenCL_FOUND` variable is set to 1, and I can successfully build it by calling `target_link_libraries(MyProject OpenCL::OpenCL)`. However, the `OpenCL_INCLUDE_DIRS` and `OpenCL_LIBRARIES` variables are not being set and are empty.

As far as I know, when `find_package` succeeds, it's a standard CMake practice for `_INCLUDE_DIRS` and `_LIBRARIES` variables to be set. I might be wrong since I'm not very familiar with CMake, but I believe this is the typical behavior in CMake.

I'm building other projects that use OpenCL, such as clFFT. In these projects, they directly reference the `OpenCL_INCLUDE_DIRS` and `OpenCL_LIBRARIES` variables in their `CMakeLists.txt` to build. Of course, I could modify the `CMakeLists.txt` files of these projects to call `target_link_libraries(SomeProject OpenCL::OpenCL)` directly, but it would be more convenient if `_INCLUDE_DIRS` and `_LIBRARIES` variables were automatically set when `find_package` succeeds. This would make it easier to work with a variety of projects.

If I'm mistaken about something, please let me know. Thanks.