In practice UTF-16 (especially from windows) uses little-endian without
a BOM. By default Qt uses host endianess which causes TIFF_XPTITLE and
TIFF_XPKEYWORDS to not be read correctly.
Fixes c21b50d699
Qt accesses the data of QImage::Format_RGBX64 and QImage::Format_RGBA64
as host-endian quint16. Having BODYChunk::deinterleave write the data
with host-endian to fix parsing on big-endian systems.
Despite the QImage::scanLine doc only warning about byte order issues
for 32-bpp formats[0] the same warning seems to apply to 16BPP formats
like QImage::Format_RGB555 as well.
[0]: https://doc.qt.io/qt-6/qimage.html#scanLine
Q_LITTLE_ENDIAN was used incorrectly, it should have been
"#if Q_BYTE_ORDER == Q_LITTLE_ENDIAN"
Use qFromBigEndian since it is more explicit.
Fixes 6d5e61f0b0
Sertonix Norson
