8068272: Extend WhiteBox API with methods that check monitor state and force safepoint

Reviewed-by: kvn, iignatyev

test/lib/sun/hotspot/WhiteBox.java

@@ -84,6 +84,8 @@ public class WhiteBox {
     return isClassAlive0(name.replace('.', '/'));
   }
   private native boolean isClassAlive0(String name);
+  public native boolean isMonitorInflated(Object obj);
+  public native void forceSafepoint();
 
   // JVMTI
   public native void addToBootstrapClassLoaderSearch(String segment);