Use c10::to_string in more places (#28605)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28605
This was added because std::to_string isn't available in libstc++
on Android. Use it in more places to get the PyTorch Android
build working with libstdc++.
Test Plan: Internal android build.
Reviewed By: jerryzh168
Differential Revision: D18099520
fbshipit-source-id: 17a2b617c2d21deadd0fdac1db849823637981fc
