Gummiboot: Switch to zip archive.

For some reason tarballs from cgit have a different hash each time you download.
Merge commit 'refs/top-bases/experimental/gimp-git' into experimental/gimp-git

# By Shea Levy
# Via Shea Levy
* commit 'refs/top-bases/experimental/gimp-git':
  Gummiboot: Switch to zip archive.
Merge branch 'master' into refs/top-bases/experimental/gutenprint

# By Shea Levy
# Via Shea Levy
* master:
  Gummiboot: Switch to zip archive.
Merge branch 'experimental/gimp-git' into refs/top-bases/experimental/gutenprint

* experimental/gimp-git:
Merge commit 'refs/top-bases/experimental/gutenprint' into experimental/gutenprint

# By Shea Levy
# Via Marc Weber (3) and Shea Levy (1)
* commit 'refs/top-bases/experimental/gutenprint':
  Gummiboot: Switch to zip archive.