Review request for 4917309 and 6864003

[Mandy Chung]

This review request is for both the HotSpot runtime and the core libs teams.

Fixed 4917309: (cl) Reduce internal usage of ClassNotFoundExceptions during 
class-loading
Fixed 6864003: Modify JVM_FindClassFromBootLoader to return null if class 
not found

Summary:
  o Fix java.lang.ClassLoader to use the new VM entry point
    JVM_FindClassFromBootLoader for load a system class from
    the bootstrap classloader that will reduce the number
    of ClassNotFoundException objects thrown by the application
    class loader by 50%.  The remaining half of the ClassNotFoundException
    objects are thrown by the extension class loader which is the parent
    of the application class loader.
  o ClassLoader.loadClass and ClassLoader.findSystemClass will
    throw ClassNotFoundException as they are specified.
  o JVM_FindClassFromBootLoader is currently not used (going to
    used by the java launcher see 6864028). There is no issue
    of changing it to return null instead of throwing CNFE.

Webrev:
   http://cr.openjdk.java.net/~mchung/4917309/hotspot-webrev/
   http://cr.openjdk.java.net/~mchung/4917309/jdk-webrev/


Thanks
Mandy