Erase array sizes from types in c10::str(). (#31683)
Summary:
This dramatically reduces the number of instantiations and eliminates
~900KB of code from my local build of libtorch_cpu.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31683
Differential Revision: D19258364
Pulled By: resistor
fbshipit-source-id: addb921a26289978ffd14c203325ca7e35a4515b
