JEP 243 changes

[Doug Simon]

I’ve just pushed changes related to https://bugs.openjdk.java.net/browse/GRAAL-53 which in turn are part of preparing Graal for JEP 243. These changes touched a lot of files and shuffled a number of packages/projects around. In particular, there’s a new com.oracle.jvmci namespace to which all the Graal code that will form the basis of JEP 243 has been moved. We will continue to refine the classes in this namespace (especially the API classes) to the absolute minimum required for implementing a Java based compile on the JVM.

These steps should help mitigate issues when you pull these changes: 

1. Delete all JDKs deployed in your Graal workspace (i.e. rm -rf jdk*)
2. mx clean
3. mx ideclean; mx ideinit

-Doug