hotspot/testlibrary references to sun.management.ManagementFactoryHelper that can easily be replaced with java.lang.management.ManagementFactory.

This will avoid any hotspot tests depending on testlibrary to include
   @modules java.management/sun.management

--- old/test/testlibrary/ctw/src/sun/hotspot/tools/ctw/CompileTheWorld.java 2015-02-25 10:14:17.812658441 -0800
+++ new/test/testlibrary/ctw/src/sun/hotspot/tools/ctw/CompileTheWorld.java 2015-02-25 10:14:17.720658440 -0800
@@ -23,7 +23,7 @@
 
 package sun.hotspot.tools.ctw;
 
-import sun.management.ManagementFactoryHelper;
+import java.lang.management.ManagementFactory;
 
 import java.io.*;
 import java.nio.file.Files;
@@ -55,7 +55,7 @@
 
         try {
             try {
- if (ManagementFactoryHelper.getCompilationMXBean() == null) {
+ if (ManagementFactory.getCompilationMXBean() == null) {
                     throw new RuntimeException(
                             "CTW can not work in interpreted mode");
                 }
--- old/test/testlibrary/ctw/src/sun/hotspot/tools/ctw/Utils.java 2015-02-25 10:14:18.180658447 -0800
+++ new/test/testlibrary/ctw/src/sun/hotspot/tools/ctw/Utils.java 2015-02-25 10:14:18.088658445 -0800
@@ -24,7 +24,7 @@
 package sun.hotspot.tools.ctw;
 
 import com.sun.management.HotSpotDiagnosticMXBean;
-import sun.management.ManagementFactoryHelper;
+import java.lang.management.ManagementFactory;
 
 import java.io.File;
 import java.util.regex.Pattern;
@@ -160,7 +160,7 @@
     public static String getVMOption(String name) {
         String result;
         HotSpotDiagnosticMXBean diagnostic
- = ManagementFactoryHelper.getDiagnosticMXBean();
+ = ManagementFactory.getPlatformMXBean(HotSpotDiagnosticMXBean.class);
         result = diagnostic.getVMOption(name).getValue();
         return result;
     }