Review Request: JDK-8165563 ClassLoader::getSystemClassLoader will never be null

[Mandy Chung]

Webrev:
  http://cr.openjdk.java.net/~mchung/jdk9/webrevs/8165563/webrev.00/

ClassLoader::getPlatformClassLoader [1] is added in JDK 9 that is parent or ancestor of the system class loader [1].  The system class loader will never be null.  Another relevant change in JDK 9 was that the system initialization was reworked that the built-in system class loader is initialized very early during startup.

This patch updates ClassLoader::getSystemClassLoader to return a non-null system class loader and the implementation of a few methods to handle the null system class loader case.

Mandy

[1] http://download.java.net/java/jdk9/docs/api/java/lang/ClassLoader.html#builtinLoaders