SilcUInt32 silc_utf8_c2w(const unsigned char *utf8,
                             SilcUInt32 utf8_len,
                             SilcUInt16 *utf8_wide,
                             SilcUInt32 utf8_wide_size);

    Converts UTF-8 string into UTF-8 wide character string into the
    `utf8_wide' buffer of size of `utf8_wide_size' in characters.  Returns
    the length of the UTF-8 wide character string or 0 on error.  The
    returned length is in characters and not in bytes.  The byte length
    is twice the returned character length.

    If there is extra space in `utf8_wide' this will NULL terminate the
    string automatically.