[PATCH 1 of 7] util: add a macro initializing CPython modules

[Jun Wu]

Excerpts from Gregory Szorc's message of 2017-05-13 13:48:18 -0700:
> FWIW, I've been thinking about merging the C modules into a single one. IMO
> there aren't many benefits to having separate C modules other than clearer
> naming. Having all the code in a single compilation unit facilitates more
> code reuse, more aggressive compiler optimization, etc. It would get a
> little weird on the pure Python / CFFI side of the world.

Moving C modules to a single file does not solve the Py2 / Py3 duplication
issue?

I have sent a V2 which solves the duplication and compiler warning issue.