The AAC decoders share no common code with the AAC encoder,
so they are not restricted to using the same structures.
This implies that one can use different structs for each
component and remove elements not used by the decoders/
the encoder. This leads to quite sizeable savings:
sizeof(ChannelElement) for the encoder went down to 134432B
here from 547552B; for the decoder it went down to 512800B.
Reviewed-by: Lynne <dev@lynne.ee>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>