Update line height in generic wxListCtrl to match images height.

Update line height in generic wxListCtrl to match images height.

The height of the items of the generic wxListCtrl remained too small if an
image of a greater than standard size was used.

Fix this by forcing the line height recalculation when adding an item using an
image higher than the current line height.

Closes #12806.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67615 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775