8172307: Remove ununsed JVM API JVM_GetModuleByPackageName()

Summary: Remove get_module_by_package_name() etc., and unneeded test.
Reviewed-by: sspitsyn, gtriantafill

test/lib/sun/hotspot/WhiteBox.java

 /*
- * Copyright (c) 2012, 2016, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012, 2017, Oracle and/or its affiliates. All rights reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -456,7 +456,6 @@ public class WhiteBox {
   public native void AddModulePackage(Object module, String pkg);
   public native void AddModuleExportsToAllUnnamed(Object module, String pkg);
   public native void AddModuleExportsToAll(Object module, String pkg);
-  public native Object GetModuleByPackageName(Object ldr, String pkg);
 
   public native int getOffsetForName0(String name);
   public int getOffsetForName(String name) throws Exception {