Fix exclude list on python 3.2+
Fix exclude list on python 3.2+

imp.get_tag() is only available on 3.2+. Since 2<x<3.2 are EOL we shall
not worry.
We could implement a local get_tag(), but the point is moot: this
compilation tactic with __pycache__ subdirs and versioned import files
is new to python 3.x, so hasattr() is sufficient.

pypa/setuptools,pypa/setuptools,pypa/setuptools