Download buck first

Change-Id: I3d293cd1d84aae38781a60e70d1e5a1342c39753
diff --git a/jjb/onos/onos-sonar.sh b/jjb/onos/onos-sonar.sh
index eb420a1..9cff485 100644
--- a/jjb/onos/onos-sonar.sh
+++ b/jjb/onos/onos-sonar.sh
@@ -10,6 +10,9 @@
 # Configure ONOS specific properties
 echo "sonar.host.url=http://sonar.onosproject.org" >>sonar-scanner-$SONAR_SCANNER_VERSION/conf/sonar-scanner.properties
 
+# Be sure buck is installed
+onos-buck --version
+
 # Generate coverage data
 tools/build/onos-prepare-sonar