Fix the locking problem reported by Pavlin when a port goes down and the intents couldn't removed.

Change-Id: Ia6deb8e8ceafaed236d03eb8fa358fb29f8eb7f2
diff --git a/src/main/java/net/onrc/onos/intent/runtime/PathCalcRuntimeModule.java b/src/main/java/net/onrc/onos/intent/runtime/PathCalcRuntimeModule.java
index b8761a4..37015cb 100755
--- a/src/main/java/net/onrc/onos/intent/runtime/PathCalcRuntimeModule.java
+++ b/src/main/java/net/onrc/onos/intent/runtime/PathCalcRuntimeModule.java
@@ -158,10 +158,11 @@
 
 	@Override
 	public IntentOperationList executeIntentOperations(IntentOperationList list) {
-		lock.lock(); // TODO optimize locking using smaller steps
 		if (list == null || list.size() == 0)
 			return null;
 		PerfLogger p = new PerfLogger("executeIntentOperations_" + list.get(0).operator);
+
+		lock.lock(); // TODO optimize locking using smaller steps
 		try {
 			// update the map of high-level intents
 			p.log("begin_updateInMemoryIntents");