Use intrusive_ptr for Blob in IValue (#16052)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/16052
We need IValue to take/return Blob as an intrusive_ptr because we want to pass it around and Blob has disabled copying.
This is needed in a diff on top.
Reviewed By: ezyang
Differential Revision: D13684761
fbshipit-source-id: 7cb3d7e9fec39a2bc9f063d4d30404e6d7016eb2
