tests: add DejaGNU framework

DejaGNU seems to be the 'standard' GNU test framework (which by itself
doesn't say much), but it seems relatively usable and the "remote
system" capabilities might come in handy for virtualisation-based tests
for kernel interactions or something.

Signed-off-by: David Lamparter <equinox@opensourcerouting.org>
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 7bc880b..14f7bef 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -1,3 +1,14 @@
+AUTOMAKE_OPTIONS    = dejagnu
+export DEJAGNU
+
+SUBDIRS =
+
+EXTRA_DIST = \
+	config/unix.exp \
+	global-conf.exp
+
+DEJATOOL =
+
 INCLUDES = @INCLUDES@ -I.. -I$(top_srcdir) -I$(top_srcdir)/lib -I$(top_builddir)/lib
 DEFS = @DEFS@ $(LOCAL_OPTS) -DSYSCONFDIR=\"$(sysconfdir)/\"