Fix CUDA jit codegen compilation with gcc-5.4 (#41055)
Summary:
It's a known gcc-5.4 bug that enum class is not hasheable by default, so `std::unordered_map` needs 3rd explicit parameters to compute hash from the type.
Should fix regression caused by https://github.com/pytorch/pytorch/pull/40864
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41055
Differential Revision: D22405478
Pulled By: malfet
fbshipit-source-id: f4bd36bebdc1ad0251ebd1e6cefba866e6605fe6
