bits_per_coded_sample should be 8.
block_align is calculated incorrectly, but it is not needed anyway.
packet pts should be calculated in samples.
packet duration can be set.

Return error if core block decoding fails.
Do not enable XCh if XCh extension block decoding fails.

If the frame is filled with the same colour, encoder may produce no data
and the fill value is indicated by zero code length (the rest of symbols
will have 0xFF for code length, meaning invalid).  So such Huffman trees
should be treated specially.
Signed-off-by: Luca Barbato <lu_zero@gentoo.org>

This prevents truncating output due to an output buffer that is too small for
all blocks. There is no limit on the number of blocks in a packet.

This fixes the requirement for the buffer size to be larger than the number of
samples actually decoded.

This stops decoding before overreads instead of after.

the decoder can handle multiple frames in a packet

For stereo we need to use intermediate planar buffers, but mono does not need
to be deinterleaved so the output buffer can be used directly.

ENOTSUP is not defined on some systems