File _constraints of Package Mesa

<constraints>
  <overwrite>
    <conditions>
      <arch>ppc</arch>
      <arch>ppc64</arch>
      <arch>ppc64le</arch>
    </conditions>
    <hardware>
      <disk>
        <size unit="G">7</size>
      </disk>
    </hardware>
  </overwrite>
</constraints>