[CM] and on osx

[Bill Schottstaedt]

If you build Snd with gtk, you need to have the "development"
version installed (so that Snd can find the gtk/cairo headers).  Try

pkg-config gtk+-2.0 --cflags

and see if the cairo directory it lists has cairo.h.  If so, please
send me config.log so I can try to see what went wrong.
If not, you could install the gtk-dev packages, or see if
any of the info in README.Snd is helpful.  As a last resort
you can build Snd without any GUI via

make clean
./configure --with-no-gui
make