Update graphviz to 15.1.0 - #535

The 15.1.0 build failed on both arches:

  I/O error: No such file or directory (os error 2) when hard linking
    graphviz-15.1.0/redhat/graphviz.spec.fedora.in
  to .../temp/.tmpXXX/redhat/graphviz.spec.rhel.in

Upstream added ONE hardlink in this release — 14.1.1 had none, which is
why it built for months:

  graphviz 14.1.1 — 0 hardlink entries
  graphviz 15.1.0 — 1 hardlink entry
    hrw-rw-rw- graphviz-15.1.0/redhat/graphviz.spec.rhel.in
               link to graphviz-15.1.0/redhat/graphviz.spec.fedora.in

The prefix-stripping extraction path cannot place a hardlink. It strips
the prefix from the entry's DESTINATION but passes the link TARGET
through verbatim — still carrying `graphviz-15.1.0/` — so the target
resolves outside the stripped tree and hard_link fails with ENOENT. Note
the two paths in the error: one keeps the prefix, one doesn't.

The no-strip path doesn't have this problem: it uses whole-archive
unpack, which resolves link targets against the destination root.

So extract with the prefix intact and `cd` into it from build.sh — the
same shape bash, binutils, bison and coreutils already use, with
`build_args = { include version }` exposing MINIMAL_ARG_VERSION.

This is a workaround, not the root fix. Any package whose upstream starts
shipping a hardlink will hit the same wall, and that belongs upstream in
the extractor rather than in each recipe.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

…tarball

Reverts the strip_prefix/hardlink workaround in 81ca043 and fixes the
actual cause, which was upstream of it.

graphviz 15.x stopped shipping the CMake build files in its release
tarball. `graphviz-15.1.0.tar.xz` is an autotools `make dist` output:

  15.1.0 release tarball   0 CMakeLists.txt, 1 hardlink,  21 MB
  15.1.0 repo archive     78 CMakeLists.txt, 0 hardlinks, 41 MB
  14.1.1 release tarball   present,          0 hardlinks, 36 MB

This recipe is CMake-based (`sed -i lib/CMakeLists.txt`, `cmake ...`), so
it cannot build from the dist tarball at all — the build failed with
`sed: can't read lib/CMakeLists.txt` because that file genuinely is not
in the archive.

Nothing changed on our side. `graphviz-15.1.0.tar.bz2` — the extension
this recipe had always used — now 404s upstream, so the resolver moved to
`.tar.xz`: same version, DIFFERENT artifact class. The hardlink I chased
in 81ca043 was a property of that wrong artifact, not a problem of its
own; the repo archive has none.

So: point at the GitLab repo archive, which carries the CMake files the
recipe needs, and restore `strip_prefix` + the original build.sh.

Verified with a local `min build --rebuild graphviz` before pushing this
time. The same command in the same session failed loudly ten minutes
earlier (`cd: graphviz-15.1.0: No such file or directory`) and now
completes clean, with and without --rebuild. Note the artifact itself
could not be inspected — `min attach -c` only accepts `min build`/`min
run`, and build outputs aren't visible from a task sandbox (minimal#978)
— so this is "builds without erroring", not "the binary was held".

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>