Adjust Automake options to build maximally portable tarballs

ChangeLog

@@ -1,3 +1,14 @@
+2021-04-20  Jacob Bachmeyer  <jcb@gnu.org>
+
+	* configure.ac: Set Automake options to use the ancient and
+	universal V7 format when building distribution tarballs.  The
+	limitations of this format are not expected to impact DejaGnu; the
+	"ustar" format will be used instead if this is proved wrong.
+
+	* Makefile.am (TAR_OPTIONS): Add exported environment variable to
+	set options when building distribution tarballs.  Ensure that all
+	files in distribution tarballs will be recorded as owned by root.
+
 2021-04-16  Jacob Bachmeyer  <jcb@gnu.org>
 
 	PR47382

Makefile.am

@@ -21,6 +21,10 @@
 AUTOMAKE_OPTIONS = dejagnu
 export DEJAGNU
 
+# record all files in the distribution tarball as owned by root
+TAR_OPTIONS = --owner=0 --group=0
+export TAR_OPTIONS
+
 EXTRA_DIST = ChangeLog-1992 MAINTAINERS dejagnu runtest \
 	$(pkgdata_DATA) $(config_DATA) $(baseboard_DATA) \
 	$(commands_DATA) $(TESTSUITE_FILES) $(TEXINFO_TEX)\

configure.ac

@@ -20,7 +20,7 @@ dnl Inc., 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
 
 AC_PREREQ([2.69])
 AC_INIT([GNU DejaGnu],[1.6.3-rc3],[bug-dejagnu@gnu.org])
-AM_INIT_AUTOMAKE([1.14 subdir-objects])
+AM_INIT_AUTOMAKE([1.14 subdir-objects tar-v7 filename-length-max=99])
 AM_MAINTAINER_MODE
 AC_PROG_MAKE_SET