Pyenv: warning about --enable-unicode in configure phase of 3.6.1

[wbolster]

running pyenv install 3.6.1 -v shows (among normal ./configure output) this warning:

configure: WARNING: unrecognized options: --enable-unicode

is this something that pyenv should address?

[wbolster]

the Misc/HISTORY for cpython contains this entry in the notes for an early 3.0 version:

- Renamed --enable-unicode configure flag to --with-wide-unicode,
  since Unicode strings can't be disabled anymore.

[methane]

Since Python 3.3, no options is needed.
Thanks to Flexible Unicode Representation, no "wide" and "narrow" build.

[yyuu]

This is adding the option as a configure options. It'd be better to skip it based on the building version....

https://github.com/pyenv/pyenv/blob/master/plugins/python-build/bin/python-build#L1978

[yyuu]

Just prepared a workaround. Though actually I've not yet tested it throughly.... Please try #978 if there's someone whom interested in this topic.