jenkins.sh: Proper error message if local environment isn't set up

Change-Id: I79c2302365824d9c8783dadfa378c8eaa07e2ee7

contrib/jenkins.sh

@@ -1,4 +1,11 @@
 #!/usr/bin/env bash
+# jenkins build helper script for openbsc.  This is how we build on jenkins.osmocom.org
+
+if ! [ -x "$(command -v osmo-build-dep.sh)" ]; then
+	echo "Error: We need to have scripts/osmo-deps.sh from http://git.osmocom.org/osmo-ci/ in PATH !"
+	exit 2
+fi
+
 
 set -ex