Back out "Delete duplicate copy of THCCachingAllocator." (#16510)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16510
This diff was supposed to be memory usage neutral, but based on
some internal flows involving cuDNN, it was not. Reverting pending
further investigation.
Original commit changeset: 03f1ebf7f11c
Reviewed By: xw285cornell
Differential Revision: D13863610
fbshipit-source-id: 15517e255fd6b0c064b65fb99f0ef19742236cfd
