EbmlUnicodeString: use UCS4 where wchar_t is four bytes long
EbmlUnicodeString: use UCS4 where wchar_t is four bytes long

The UTFstring class copies directly from wchar_t * strings. This means
that its internal representation must be compatible with the C++
library's implementation of wide-char strings. For most (all?) Unix
platforms wchar_t is four bytes long and strings are encoded in UCS4,
not 2.

Matroska-Org/libebml,Matroska-Org/libebml