Define std::strtoll for older Android (#28603)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28603
This symbol isn't availble in older Android configs, so import it
from the global namespace in the same file as the rest of our
Android string compatibility hacks.
Test Plan: Internal android build.
Reviewed By: jerryzh168
Differential Revision: D18099515
fbshipit-source-id: f8b0c80ea7344e05975a695afb359b339b6d9404
