Windows handles wchar_t* UTF-16 and char* ANSI (presently UTF-8)
filenames using alternative -A and -W API. We'll try them both
when opening a file. This means that you should not worry about
about conversions.
Fixes#1098 and !76.
* builds/windows/ftsystem.c (FT_Stream_Open): Call alternative
`CreateFile` in the case of failure.