Change directory pointing to StdFace submodule

[yomichi]

Short summary

After this PR,

• Users should download the source code via git clone or the tarball files attached to the release page, HPhi-X.Y.Z.tar.gz
• Developers should attach the tarball file including the static copy of submodules (StdFace) to the release page

Details

git submodule is a good mechanism to deal with other git repositories, but it works only when the repository is cloned although we sometimes want to use a tarball file instead.

• Before the PR
  • If the directory is git cloned
    • StdFace is automatically downloaded by git submodule update -i -r int src/StdFace/submodule in the cmake process
  • If not
    • StdFace is automatically downloaded by git clone into src/StdFace/cloned in the cmake process
    • Unfortunately, this does not work well if the machine is inside a firewall (e.g., some supercomputers)
• After the PR
  • If the directory is git cloned
    • StdFace is automatically downloaded by git submodule update -i -r int src/StdFace in the cmake process
  • If not
    • Do nothing. It is assumed that StdFace exists at src/StdFace.
    • Archive files should includes the proper StdFace at src/StdFace.
      • This can be easily done by git-archive-all tool.
        • dist.sh is updated to use git-archive-all
      • We (developers) should attach the archive file to the release page.