am e022cb08: Merge "Don\'t attempt to stop the receive thread if we never started it." into mnc-dev

* commit 'e022cb085f6ebc2801f843bb47c9fd23f6daa3ea':
  Don't attempt to stop the receive thread if we never started it.

services/net/java/android/net/dhcp/DhcpClient.java

@@ -603,7 +603,10 @@ public class DhcpClient extends BaseDhcpStateMachine {
         @Override
         public void exit() {
             cancelOneshotTimeout();
-            mReceiveThread.halt();  // Also closes sockets.
+            if (mReceiveThread != null) {
+                mReceiveThread.halt();  // Also closes sockets.
+                mReceiveThread = null;
+            }
             clearDhcpState();
         }