Byte-compilation for pypy3

[Stefano Rivera <stefanor@debian.org>]

So, I've had some pypy3 packages sitting around for a while, and the
main thing that's stopped me from uploading, is figuring out a plan for
byte-compilation.

If it's sharing /usr/lib/python3/dist-packages with cPython (which it
currently is) then we should figure out a plat for byte-compiling for
it.

rtupdate and postinst / prerm hooks for python3 packages currently call
py3{compile,clean} which only operates on cpython3.

Options I can think of:
1. Ignore byte-compilation entirely.
2. Change py3{compile,clean} to call pypy3{compile,clean} too.
   And do some extra compiling / cleaning when pypy3 is installed and
   removed.
3. Change py3{compile,clean} to do the work of pypy3{compile,clean} too.
   And do some extra compiling / cleaning when pypy3 is installed and
   removed.
4. Change the snipets dh_python3 generates, to include
   pypy3{compile,clean}, when they exist. And again, do the extra
   compiling / cleanup.
5. Something else?

3 *seems* like the right option - py3{compile,clean} supports a range of
cpython versions, already. But I'm not really sure.

Here's what I've got:
https://salsa.debian.org/debian/pypy3
https://people.debian.org/~stefanor/pypy3/

Other TODOs that need some attention but possibly aren't blocking an
upload to unstable:
* test failures and errors
* import paths aren't quite right, yet, e.g.:
  - setup.py install installs to a /usr/local path that isn't on
    sys.path
  - plat-linux2 is on sys.path, but doesn't exist

SR

-- 
Stefano Rivera
  http://tumbleweed.org.za/
  +1 415 683 3272