elm_box: Fix support of aspect hints

Test scenario: ephoto without a recent patch (47fe2b9ab03c151b0f4).
Before any further explanation, ephoto was definitely misusing the
aspect API here. A label most definitely shouldn't be sized based on an
aspect ratio, that's just crazy (you really want to make it as tall as
it's wide?)

If a box has an aspected item, it needs to run its min calc loop twice:

1. Once to determine the "true" min size in the direction of the box (ie. in X in case of a horizontal box), and
2. Once more in order to apply the aspect ratio to aspected items and augment the perpendicular min size (ie. Y for horizontal).

After that, it can go and layout the items based on the available size.

As we may guess from the above description (1) determines min W and
(2) determines min H (in horizontal mode).

BUT, there were two problems:

• The wrong item min size was used inside the 2nd loop (the code was not symmetrical between horizontal and vertical modes). These are the changes in _smart_extents_non_homogeneous_calc.
• The box min length was based on the actual size of aspected items, rather than their min size. This goes against the observation. These are the changes in _smart_extents_calculate.

Ref T5888

@fix