Review Request: JDK-8161121: VM::isSystemDomainLoader should consider platform class loader

[Mandy Chung]

With deprivileging, several modules of the runtime are mow defined to 
the platform class loader.  VM::isSystemDomainLoader is extended to
detect if the given class loader is boot loader or platform loader.

Webrev: 
  http://cr.openjdk.java.net/~mchung/jdk10/webrevs/8161121/webrev.00/index.html

thanks
Mandy