replacing THC_CLASS and THC_API with TORCH_CUDA_API (#49690)
Summary:
THC_API and THC_CLASS were leftover macros from before the consolidation of caffe2, aten, and torch. Now that they're combined, these are misleading and should just be TORCH_CUDA_API. The only file I manually edited was `THCGeneral.h.in`.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49690
Reviewed By: malfet
Differential Revision: D25667982
Pulled By: janeyx99
fbshipit-source-id: 2fdf7912b2a0537b7c25e1fed21cc301fa59d57f
