bug#37563: 27.0.50; fit-frame-to-buffer does not account for line-spacing

[martin rudalics]

> 4) *My interpretation* of `frame-resize-pixelwise' is that the default
> value, nil, has a single intention: To make the frame height an exact
> multiple of lines (and char width), mainly because of aesthetic reasons.
> In that case, I suggest we change the doc-string (which has some
> inaccurate phrasing and is a bit wordy, anyway) to say that it nil will
> round to a multiple of the default line height (incl line spacing)..

We cannot reliably do that.  Suppose a frame has two windows with
different line heights.  Which one would we choose for rounding the
frame size?  'frame-char-height' is canonical.

martin