
Bundling of vulkan-headers

The source includes debian/sync_headers.sh script, which is used
to bundle a matching version vulkan-headers. This makes sure that
the built library has a correct SONAME.

The procedure to update to a new upstream release goes usually like
this:

# git checkout upstream-unstable
# git reset --hard vulkan-sdk-<new version>
# git checkout -b d-u
# git merge -s ours vulkan-sdk-<old version>
# git merge debian-unstable
# git mergetool
#  sort out conflicts, the generated files should stay deleted from
#  the packaging branch
# git branch -M debian-unstable
# dch -v <new version>; git commit -a -m "version bump"
# debian/sync_headers.sh
# debian/rules gentarball
