version: include version information for tarballs from git

Embed the git commit hash as well as the tag information for tarballs
produced by 'git archive' (this includes the Github tarball). Example:

    TShark (Wireshark) 3.0.1 (Git commit ea351cd80516)

Note that the embedded git ref names can include branch information, see
for example `git log -n1 -s --format=%D v3.0.1`:

    tag: wireshark-3.0.1, tag: v3.0.1
    HEAD -> bug/15544, tag: v99.99
    HEAD, origin/master, origin/HEAD, master

Thus, when creating release tarballs, I would recommend using the above
command to see whether unnecessary branch information is present. If so,
create a new post-release commit first on the same branch. This way, the
release tarballs should be reproducible.

While at it, increase the commit abbreviation length from 8 to 12.
Currently git describe abbreviates to 10 by default. The default length
is at minimum 7 and is dependent on the number of objects:

    git count-objects -v | perl -lne 'print int(log($1)/log(2)/2)+1 if /^in-pack: (\d+)/'

Bug: 15544
Change-Id: Ifd1ed636b69f7687a7272775686f51387040a596
Reviewed-on: https://code.wireshark.org/review/33214
Petri-Dish: Peter Wu <peter@lekensteyn.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Dario Lombardo <lomato@gmail.com>
Reviewed-by: Alexis La Goutte <alexis.lagoutte@gmail.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/.gitattributes b/.gitattributes
index 26b401002e..c9ca36b067 100644
--- a/.gitattributes
+++ b/.gitattributes
@@ -5,3 +5,4 @@
 .gitattributes              export-ignore
 .gitignore                  export-ignore
 .gitreview                  export-ignore
+tools/make-version.pl       export-subst