turn off autograd mode in android JNI wrapper (#26477)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/26477
- At inference time we need turn off autograd mode and turn on no-variable
mode since we strip out these modules for inference-only mobile build.
- Both flags are stored in thread-local variables so we cannot simply
set them to false glboally.
- Add "autograd/grad_mode.h" header to all-in-one header 'torch/script.h'
to reduce friction for iOS engs who might need do this manually in their
project.
P.S. I tried to hide AutoNonVariableTypeMode in codegen but figured it's not
very trivial (e.g. there are manually written part not covered by codegen).
Might try it again later.
Test Plan: - Integrate with Android demo app to confirm inference runs correctly.
Differential Revision: D17484259
Pulled By: ljk53
fbshipit-source-id: 06887c8b527124aa0cc1530e8e14bb2361acef31
