/*
   * Iterate over all to-be-removed-without-replacement solvables
   * those replaced by an updated are normally *not* reported.
   *
   * if +true+ is passed, iterate over *all* to-be-removed solvables
   *
   * call-seq:
   *  solver.each_to_remove { |solvable| ... }
   *  solver.each_to_remove(true) { |solvable| ... }
   *
   */
  void each_to_remove(int bflag = 0)