The 'hurd-minimal' package (via hurd-headers) now uses a git checkout and
added dependencies on autoconf, automake and teiinfo to build. Using those in
commencement creates a bootstrap loop. So, revert to a tarball release.
* gnu/packages/commencement.scm (hurd-minimal-boot0): Build from tarball;
remove autoconf, automake, texinfo bootstrap dependencies.