Emit script function calls during tracing. (#25089)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/25089
Previously, when the tracer encountered a scripted function (or method), it
inlined the function into the graph. Now, we emit a CallFunction or
CallMethod node instead.
Test Plan: Imported from OSS
Reviewed By: zdevito
Differential Revision: D16987936
Pulled By: suo
fbshipit-source-id: a3e38a4621f3504909ec0542865dc7e381c243d6
