Fix output on big-endian systems

[roderickvd]

No idea if anyone is using librespot on big-endian systems, but this makes it so output is always in native endian format. This already was OK on the rest of the backends, and for Alsa it only concerned S24_3.

[JasonLG1979]

Sure why not. Off the top of my head, old Power PC Macs are Big Endian.

[JasonLG1979]

I would assume that lewton decodes to the native endianness of the platform then?

[roderickvd]

I think so. It uses byteorder.

[JasonLG1979]

I think so. It uses byteorder.

It's so hard to really test this. I guess we'll find out if our assumptions are correct or not if it fails for someone on some obscure hardware?

[roderickvd]

Yeah best we can do is a code review. At least this makes it more consistent, because the gating on #[cfg(target_endian = "little|big")] is exactly what alsa::Format::float() and friends do.

Honestly I wouldn't be surprised if no-one were playing on a big-endian system so this is just good housekeeping.