I'm not 100% sure if this was breaking SSE41 builds on the official build system (I'm building Pipewire
with a different process), but I suspect it was, because you can't combine these into a single translation
unit to sidestep it without including multiple copies of resample-native-impl.h which isn't desirable.
Make a new uint42_t and int24_t type and use that to handle 24 bits
samples. This makes it easier because we can iterate and copy the
structs like other types.
Pass some state to convert and channelmix functions. This makes it
possible to select per channel optimized convert functions but
also makes it possible to implement noise shaping later.
Pass the channelmix matrix and volume in the state.
Handle specialized 2 channel s16 -> f32 conversion
