[CM] Getting snd to work with conjure/neovim

[bil at ccrma.Stanford.EDU]

This appears to be some pipe issue with stdin -- if
you run Snd from a terminal, then type expressions
in that terminal, get_stdin_string is called and
the expressions are evaluated, etc.  If you call
Snd as a target of a pipe (or whatever the correct
terminology is), it works once, but then stdin is always
"ready to be read", so XtAppAddInput is in a loop
calling it to no purpose (0 bytes read).  If I add
something like
   if (ioctl(fileno(stdin), FIONREAD, &n) == -1 || n == 0) return;
and try to type input, it never gets read.  The
Motif docs say this sort of input is "unreasonable".