[CM] SND on OSX

[Bill Schottstaedt]

 > ld: Undefined symbols:
 > _cacos
 > [...]
 > _SCM_VARIABLE_REF
 > make: *** [snd] Error 1

The first (cacos) looks like a bug in my configure script --
it's supposed to try to fallback on gsl if there's no built-in
complex trig support.  I'll stare at that code some more.

The second is similar to a bug reported to me by Stanko
Juzbasic (on the SGI) that has me a bit mystified.  That
macro (SCM_VARIABLE_REF) has been in Guile forever, but
for some reason it is confusing various compilers -- I'll
stare at this also.

 > snd-gfile.c: In function `prune_file_list':
 > snd-gfile.c:335: error: void value not ignored as it ought to be

I need to look at the gtk changelogs (at home) -- my first
guess is that something changed after gtk 2.0, and I didn't notice
the backwards incompatibility.  This part of Snd's gtk code is a
horrible temporary kludge anyway -- I wanted the "just-sounds"
button to work despite gtk's less-than-adequate file selection
widget, so I was messing around in the guts of the dumb thing.
They have subsequently provided what appears to be a much better
file chooser, with (I think) built-in hooks for the sort of thing
I wanted to do here, but I haven't had time yet to look at it
very closely.