This is being added straight to 4.2, prior to the `make license` command
which will use this to generate a more complete license file.
Licenses information and ambiguities worked with Dalai Felinto.
Part of !129018.
`BLI_strncpy_wchar_from_utf8` internally assumes `wchar_t` is 32 bits
which is not the case on windows.
The solution is to replace `wchar_t` with `char32_t`.
Thanks to @robbott for compatibility on macOS.
Differential Revision: https://developer.blender.org/D6198