[CM] file-size limit in snd?

[Bill Schottstaedt]

I think Snd works now in general with any size file: I tested it
pretty fully with a 44.1KHz 20 hour sine wave (its amplitude
was changing, so I didn't get bored).  sndinfo and sndplay also
need to be recompiled.

I'm not immediately sure how to get CLM to work in this regard --
it could write and play such files, but I need some way to
deal with long longs (64-bit ints) in the foreign function
interface.