guile on mac OSX

[Bill Schottstaedt]

Guile 1.4.1 builds and works fine in Mac OS-X (developer
version), but there's one small glitch in the configure
process -- it doesn't recognize the name "Darwin" as the
OS name (I think -- I'm no Mac or configure expert).
The mac-supplied config.guess and config.sub (from
/usr/libexec) do work.  I could send the relevant diffs,
if there's interest.