HADOOP-13858. TestGridmixMemoryEmulation and TestResourceUsageEmulators fail on the environment other than Linux or Windows.

(cherry picked from commit 98c35bb1a4faf794060612bee7494d501701b698)

hadoop-tools/hadoop-gridmix/src/test/java/org/apache/hadoop/mapred/gridmix/DummyResourceCalculatorPlugin.java

@@ -31,6 +31,10 @@ import org.apache.hadoop.yarn.util.ResourceCalculatorPlugin;
 @InterfaceAudience.Private
 public class DummyResourceCalculatorPlugin extends ResourceCalculatorPlugin {
 
+  DummyResourceCalculatorPlugin() {
+    super(null);
+  }
+
   /** max vmem on the TT */
   public static final String MAXVMEM_TESTING_PROPERTY =
       "mapred.tasktracker.maxvmem.testing";