Math functions of c10::complex should be overloaded as const reference (#37689)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37689
It has to be this way, otherwise, we will not be able to use it in vec256 because the function pointers declared there are using const reference.
Test Plan: Imported from OSS
Differential Revision: D21394603
Pulled By: anjali411
fbshipit-source-id: daa075b86daaa694489c883d79950a41d6e996ba
