Set RecordFunction id only when needed (#39265)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39265
In this PR we set id of RecordFunction only when callbacks need them and when
there's at least one active callback
Test Plan:
testRecordFunction unit test in test_misc.cpp
buck test mode/dev caffe2/test/cpp/jit:jit
https://our.intern.facebook.com/intern/testinfra/testrun/8725724291116413
Reviewed By: dzhulgakov
Differential Revision: D21790421
fbshipit-source-id: 016623d7f1a2a271921a71c0483061e232b40321
