bug#24820: Imenu in `python-mode' does not display function name for async def

[npostavs]

Dmitry Lazurkin <dilaz03@gmail.com> writes:

> Some fixes:
> - fix commit message
> - return imenu type "async def" for async def's

Thanks.  I'll push this to master in a week or so, unless there are
objections.

> (is formatting code ugly?)

I don't see any formatting problems in your code, but it looks like the
patch got word wrapped, I find sending as attachment generally avoids
such issues.

> -         (type)
> -         (name (when (and pos (looking-at
> python-nav-beginning-of-defun-regexp))
> -                 (let ((split (split-string
> (match-string-no-properties 0))))