Intoducing bfloat16 type (#21522)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21522
ghimport-source-id: 4803f197ec04938501fdb10c1741280331c349d2
Test Plan: Imported from OSS
Differential Revision: D15819369
Pulled By: izdeby
fbshipit-source-id: 46408dc316a5c4dc644a736dc42da2422b34bcb9
