Support building wheels (PEP-427)

Universal is used to identify pure-Python module(by bdist_wheel).
For these, it is sufficient to build a wheel with _any_ Python ABI
version and publish that to PyPI (by whatever means).

Change-Id: I4e93aef95706e298c3ef91f1690e2ef8ce944405
Merge "Support building wheels (PEP-427)"