This makes the logic in UTF16BEToUTF8() match UTF16LEToUTF8().
* encoding.c:
(UTF16LEToUTF8):
- Fix comment to describe what the code does.
(UTF16BEToUTF8):
- Fix undefined behavior which was applied to UTF16LEToUTF8() in
2f9382033e.
- Add bounds check to while() loop which was applied to
UTF16LEToUTF8() in be803967db.
- Do not return -2 when (in >= inend) to fix the bug. This was
applied to UTF16LEToUTF8() in 496a1cf592.
- Inline (<< 8) statements to match UTF16LEToUTF8().
Add the following tests and results:
test/text-4-byte-UTF-16-BE-offset.xml
test/text-4-byte-UTF-16-BE.xml
test/text-4-byte-UTF-16-LE-offset.xml
test/text-4-byte-UTF-16-LE.xml
