Make wcwidth.c use uint32_t instead of wchar_t

The functions in `wcwidth.c` are based on the assumption that `wchar_t` is UCS-4 encoded, while windows uses UCS-2, which was causing some warnings on windows builds. The corresponding `-Wno` flags have been removed.

Note that, even with this change, `TTF_RenderGlyph_Solid`, `TTF_RenderGlyph_Blended` (for SDL builds) and `ExtTextOutW` (for non-SDL windows builds) only support drawing 16 bit characters, so we still can't use characters outside of the Basic Multilingual Plane on non-curses builds.

This builds off of #3127
See #3141