LunarLander: Fix race condition causing crash on exit

When exiting the LunarLander sample, it was possible for the canvas
to get destroyed before execution was halted.

Added additional synchronization to make sure the current run-state
is accounted for before performing a canvas update.

Also updated deprecated constants in lunar_layout.xml.

Bug: 6164549
Change-Id: I9a710f6b128491f1beece84dd39ab00f4937a4c6

samples/LunarLander/src/com/example/android/lunarlander/LunarLander.java

@@ -149,8 +149,8 @@ public class LunarLander extends Activity {
      */
     @Override
     protected void onPause() {
-        super.onPause();
         mLunarView.getThread().pause(); // pause game when Activity pauses
+        super.onPause();
     }
 
     /**