File _service of Package llvm

<services>
  <service name="tar_scm">
    <param name="url">https://github.com/ziyao233/eweos-packages.git</param>
    <param name="revision">llvm</param>
    <param name="scm">git</param>
    <param name="extract">*</param>
  </service>
  <service name="download_files" />
</services>