Update openstack.common.policy from oslo

To fix an issue about ConfigFilesNotFoundError.

Oslo commit is aae2b1c38801ac8f00f817a17b1b0916a8d7c2c3.

Closes-bug: #1236177
Change-Id: I24c1d80033fc8166e7b1de01499f6d247b166f88
Merge "Update openstack.common.policy from oslo"