Improve cpu/Loops.h arity asserts. (#38809)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/38809
This splits the asserts into separate input/output asserts and makes the numbers precise, instead of ranges.
This is an ongoing effort to improve the Loops assertion and to integrate dynamic cast checking into CPU loops.
Test Plan: Imported from OSS
Differential Revision: D21670263
Pulled By: gchanan
fbshipit-source-id: b1868db5255a69158045b759dc9171690a2dcd01
