lang/python{27,3*}: Backport upstream issue 20397 patches

[koobs]

Summary

Commit log:

lang/python{27,3*}: Backport patch in upstream issue20397

In certain situations, file references (.py[co]) for Python files that
fail to compile with compileall() are still added to distutils --record
output.

This output is used for pkg-plist generation and must only contain
references to files that will be installed.

One example of a failure condition is when a Python 2/3 compatible
package containing a file containing Python 3.x only code is built with
Python 2.x, such as Gunicorn's _gaiohttp.py [1]

This change backports patches submitted against upstream issue 20397 [2]
that has not yet been committed.

 - For Python 2.7 and 3.5, backport both install_lib and test
 - For Python 3.2, 3.3 and 3.4, only backport install_lib

[1] https://svnweb.freebsd.org/changeset/ports/404558
[2] https://bugs.python.org/issue20397

Thank you to Brendan Molloy for producing the patches against upstream

MFH:		2016Q1
Reviewed by:
DiffRev:	D4832

Test Plan

• portlint: OK (no changes, i want to keep this backport commit isolated for MFH)
• testport: OK (poudriere, 11amd64, 102amd64, 93i386)
• gunicorn: OK (test www/py-gunicorn no longer fails without r404558 workaround)

[sbz]

LGTM

[miwi]

Well done!