* Process status now synchronized as follows: new primitive

* Process status now synchronized as follows: new primitive
  `process-status-sync' freezes the status and exit reason, returning
  #T if it has changed since the last synchronization, or #F if it
  hasn't changed.  Primitives `process-status' and `process-reason'
  return the frozen status information but do not affect the
  synchronization.

* Primitives `process-wait' and `process-continue-foreground' no
  longer return a value.  Previously they returned the process status.