Adapt to llvm marking SmallVector::set_size private (#71434)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71434
See also https://reviews.llvm.org/D115380
Reviewed By: zhuhan0
Differential Revision: D33638540
fbshipit-source-id: a55e51462dc0d8f55a75bb79d9d76db781a36af2
(cherry picked from commit 78d1d65f77ab575acb367196608606206d29b0f1)
