Reset hover item when mouse leaves wxAuiToolBar.

Reset hover item when mouse leaves wxAuiToolBar.

The hover item was not reset properly in some circumstances, do it now.

Also check for the item being disabled in SetHoverItem() itself instead of
doing it several times before calling it.

Closes #14189.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@71210 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775