el_getc() for the WIDECHAR case, that is, the version in eln.c.
For a UTF-8 locale, it is broken in four ways:
1. If the character read is outside the ASCII range, the function
does an undefined cast from wchar_t to char. Even if wchar_t
is internally represented as UCS-4, that is wrong and dangerous
because characters beyond codepoint U+0255 get their high bits
truncated, meaning that perfectly valid printable Unicode
characters get mapped to arbitrary bytes, even the ASCII escape
character for some Unicode characters. But wchar_t need not
be implemented in terms of UCS-4, so the outcome of this function
is undefined for any and all input.
2. If insufficient space is available for the result, the function
fails to detect failure and returns garbage rather than -1 as
specified in the documentation.
3. The documentation says that errno will be set on failure, but
that doesn't happen either in the above case.
4. Even for ASCII characters, the results may be wrong if wchar_t
is not using UCS-4.
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