Move THCCachingAllocator to c10_cuda. (#16119)
Summary:
Some renaming and renamespacing also took place. I was originally planning not to do anything, but it turns out that it was easier to make HIPify work by using a namespace CUDACachingAllocator:: rather than THCCachingAllocator_, since :: is a word boundary but _ is not.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16119
Reviewed By: smessmer
Differential Revision: D13718768
fbshipit-source-id: 884a481d99027fd3e34471c020f826aa12225656
