better coding style in darwin disc_read
better coding style in darwin disc_read

Only fixing that one function, since it was recently changed a bit,
so we have consistent style at least in the function.
Other fixes should be made with other code changes.

I am not necessarily fond of tab indentation, but that is
what the main files are using.

metabrainz/libdiscid,phw/libdiscid,phw/libdiscid,metabrainz/libdiscid