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/configure.ac b/configure.ac
index 6e59037..582f357 100755
--- a/configure.ac
+++ b/configure.ac
@@ -1619,6 +1619,18 @@
 AC_SUBST(PICFLAGS)
 AC_SUBST(PILDFLAGS)
 
+dnl -------
+dnl DejaGNU
+dnl -------
+if test x"$DEJAGNU" = x
+then
+  DEJAGNU="\$(top_srcdir)/tests/global-conf.exp"
+fi
+RUNTESTDEFAULTFLAGS="-x --tool \$\$tool"
+
+AC_SUBST(DEJAGNU)
+AC_SUBST(RUNTESTDEFAULTFLAGS)
+
 dnl ------------------------------
 dnl set paths for state directory
 dnl ------------------------------
@@ -1691,8 +1703,8 @@
 AC_CONFIG_FILES([Makefile lib/Makefile zebra/Makefile ripd/Makefile 
 	  ripngd/Makefile bgpd/Makefile ospfd/Makefile watchquagga/Makefile
 	  ospf6d/Makefile isisd/Makefile babeld/Makefile vtysh/Makefile
-          doc/Makefile ospfclient/Makefile tests/Makefile m4/Makefile
-          redhat/Makefile
+	  doc/Makefile ospfclient/Makefile tests/Makefile m4/Makefile
+	  redhat/Makefile
 	  pkgsrc/Makefile
 	  redhat/quagga.spec 
 	  lib/version.h