See https://github.com/spk121/guile100
* bin/tar.in: New file.
* configure: Produce bin/tar.
* .gitignore: Ignore it.
* makefile (bin/tar): New target.
* gash/tar.scm: New file.
* gash/ustar.scm: New file.
* build-aux/build-guile.sh: Compile new files.