jrt file system now has /package and /modules directories

[Alan Bateman]

Just a heads-up that jdk9-b74 has a refresh of the jimage and jrt file 
system implementation.

For IDEs and other tools that are using the jrt file system then an 
important change in this build is the addition of the /packages and 
/modules top-level directories in the file system. Details in 
JDK-8066492 [1].

-Alan.

[1] https://bugs.openjdk.java.net/browse/JDK-8066492