Vectorize complex copy. (#44722)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/44722
Signed-off-by: Edward Z. Yang <ezyang@fb.com>
Test Plan: Imported from OSS
Reviewed By: anjali411
Differential Revision: D23731276
Pulled By: ezyang
fbshipit-source-id: 4902c4b79577ae3c70aca94828006b12914ab7f9
