working GetMinMBCharWidth(): the idea is that we can't deal with completely arbitrary encodings anyhow using the current API as we get confused by NUL runs in the middle of the string, so instead just deal correctly with normal multibyte encodings, UTF-16/UCS-2 and UTF-32/UCS-4 which should cover 99.9% of the cases git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@38523 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775