Add a node reference to agent ubuntu16.04-basebuild-8c-15g node

Change-Id: I3c6bdd52580c0797ea8abcf6947a607f5f46d942
diff --git a/tools/build/jenkins/onos-buck-gerrit b/tools/build/jenkins/onos-buck-gerrit
index 64b62f2..1a3eb5f 100644
--- a/tools/build/jenkins/onos-buck-gerrit
+++ b/tools/build/jenkins/onos-buck-gerrit
@@ -2,7 +2,7 @@
 
 pipeline {
 
-    agent any
+    agent { node { label 'ubuntu16.04-basebuild-8c-15g' } }
 
     stages {