Add count_include_pad arg for average_pool_op on CPU (#15593)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/15593
Add count_include_pad arg for average_pool_op on CPU
Reviewed By: houseroad
Differential Revision: D13558123
fbshipit-source-id: 188879ec3af313105ff66ac0b5a81ea44fca2855
