create_tarball: Convert to UTC the date of the last commit,

which is written to '.tdescminfo'.

Because formatting a date using 'git log' does not return results in UTC,
the unix timestamp is used for git log, and conversion to UTC is done
using 'date'.

It addresses time zone independence to ensure a reproducible build.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit 517a783020)

create_tarball

@@ -157,7 +157,7 @@ if [ ! -e $TARBALL_DIR/$package.tar$TAR_SUFFIX ]; then
   echo "# TDE SCM module information" > .tdescminfo
   echo "Name: $MODULE" >> .tdescminfo
   echo "Revision: $branch-$(git rev-parse HEAD)" >> .tdescminfo
-  git log -1 --pretty=format:"DateTime: %cd%n" --date=format:"%m/%d/%Y %H:%M" >> .tdescminfo
+  date +"DateTime: %m/%d/%Y %H:%M" -u -d "@$(git log -1 --pretty=format:"%ct")" >> .tdescminfo
   trap "rm $TARBALL_DIR/tar-$$; rm .tdescminfo; exit 1" INT
   find ./ -print0 | LC_ALL=C sort -z | \
   tar c --no-recursion --null -T - \