track Half/ComplexHalf default dtype (#45043)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/45043
Test Plan: Imported from OSS
Reviewed By: ezyang
Differential Revision: D23806097
Pulled By: bhosmer
fbshipit-source-id: 1c816b09c1e6b3c7ba85ed43d8e6c2518a768da4
