8140802: Clean up and refactor of class loading code for CDS

Reviewed-by: jiangli, acorn

modules.xml

@@ -340,6 +340,7 @@
       <to>java.sql</to>
       <to>java.sql.rowset</to>
       <to>jdk.scripting.nashorn</to>
+      <to>jdk.vm.cds</to>
     </export>
     <export>
       <name>sun.reflect.annotation</name>

test/lib/sun/hotspot/WhiteBox.java

@@ -407,6 +407,7 @@ public class WhiteBox {
   public native void assertMatchingSafepointCalls(boolean mutexSafepointValue, boolean attemptedNoSafepointValue);
 
   // Sharing
+  public native boolean isSharedClass(Class<?> c);
   public native boolean isShared(Object o);
   public native boolean areSharedStringsIgnored();
 }