[Distutils] Letting the Python implementation produce the Python ABI tag

[Squeaky]

Hi!

This is my first message to this mailing list. I saw a discussion about 
construction of SOABI and I thought that it might be tiresome to keep 
code to produce that for every possible Python implementation in wheel 
generators. After all it's the Python implementation that knows better 
in which version and why they broke binary ABI.

Let's say that PyPy 2.2 has this tag set to pp22 but they might have 
released PyPy 2.3 without breaking the ABI and prefer to advertise 
PyPy2.3 as pp22 compatible thus reducing the number of wheels a python 
package maintainer has to produce. The ABI is separate from releases.

Also this would benefit if there were new Python implementations coming 
into ecosystem and they could have a function in their stdlib that 
advertises their abi level. This would allow these new implementations 
to work with wheels instantly.

Does it make sense or it's an utopia?

Regards,
Squeaky