[JIT] dont count constants in subgraph size (#41436)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/41436
Constants are not executed as instructions, we should ignore them when counting subgraph size, as we ignore them in counting block size for loop unrolling.
Test Plan: Imported from OSS
Reviewed By: Krovatkin, ZolotukhinM
Differential Revision: D22600608
Pulled By: eellison
fbshipit-source-id: 9770b21c936144a3d6a1df89cf3be5911095187e
