/*
   * Allow arch change
   *
   * After installation, the architecture of a package is fixed an the
   * solver will not change it during upgrades.
   * This prevents updates to a higher version but inferior
   * architecture.
   * If this flag is set, packages can change their architecture. The
   * solver will usually try to select the 'best' architecture.
   *
   * call-seq:
   *  solver.allow_arch_change -> bool
   *
   */
  int allow_arch_change()