add basic CTRL interface tests

Prepare for adding tests of enable-/disable-/status-ps CTRL commands.

Change-Id: Ie195169c574716b514da7e04a3ce9727ef70a55e
diff --git a/contrib/jenkins.sh b/contrib/jenkins.sh
index e2abb60..b08c63b 100755
--- a/contrib/jenkins.sh
+++ b/contrib/jenkins.sh
@@ -35,7 +35,7 @@
 
 cd "$base"
 autoreconf --install --force
-./configure
+./configure --enable-external-tests
 $MAKE $PARALLEL_MAKE
 if [ "x$label" != "xFreeBSD_amd64" ]; then
     $MAKE check || cat-testlogs.sh