Fix missing header (#34762)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/34762
So far it's by luck that we somehow include "caffe2/core/tensor.h" before including "caffe2/caffe2/quantization/server/fbgemm_pack_blob.h". This is not safe and this diff fixes it.
Test Plan: unittest
Reviewed By: jianyuh
Differential Revision: D20455352
fbshipit-source-id: 777dae32a23d0ec75fd7e5e1627426b5a5f81f5a
