Fix empty_like for quantized tensors. (#21978)
Summary:
empty_like uses the tensor options of `self`, rather than the passed in tensor options. This means it messes up variable/tensor types, and ignores specifications like different dtypes.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21978
Differential Revision: D15903948
Pulled By: gchanan
fbshipit-source-id: f29946be01c543f888daef2e99fe928e7b7d9d74
