Snd 12.4.

  removed thread support from Snd/s7/sndlib.
  removed snd9.scm.

  s7 is nearing the point where we can get rid of the run macro.
  Currently the fm-violin in C takes 400 callgrind units to generate
  20 seconds of sound, in run it takes 480, and in s7 by itself, 700.
  In Snd 12.2, s7 took 4896, in Snd 11.10 from last August, 7392.


checked: sbcl 1.0.50, gtk 3.1.10|12

Thanks!: Mike Scholz

