Decouple JIT and autograd codes (#28900)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/28900
Decouple the JIT and autograd codes (and their dependencies). After this decoupling, the compressed torch mobile size is 548 KB total (comparing to 2.98 MB with full JIT).
ghstack-source-id: 93447313
Test Plan: buck build fbandroid/mode/dev_clang_libcxx //xplat/experimental/pytorch/mobile:lite_predictorAndroid#android-armv7 -c project.ignore= -c user.ndk_cxxflags=-g0 --show-output
Differential Revision: D18226237
fbshipit-source-id: a188329274b450f63eb6448f42adec28517e14fd
