The OpenGL headers are not always implicitly available, so this improves the check by calling `find_package` and using the `OPENGL_INCLUDE_DIRS` or `OPENGL_INCLUDE_DIR` var for the `check_c_source_compiles` test.
The minimum CMake version currently set is 3.16, `OPENGL_INCLUDE_DIRS` was only added in 3.29, so the code is set to choose `OPENGL_INCLUDE_DIRS` if it exists. If the minimum CMake version is ever set to >= 3.29 this check can be removed and just the `OPENGL_INCLUDE_DIRS` variable can be chosen.