Let users pass CMake-specific options starting with CMAKE_ to CMake. (#22776)
Summary:
This should make it more convenient to follow https://github.com/pytorch/pytorch/issues/8433's suggestion.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/22776
Differential Revision: D16493553
Pulled By: ezyang
fbshipit-source-id: 852f4779e70f84a4c9f7bab4c2ae4927248ffc93
