8031498: Cleanup and re-factorize PhaseChaitin::build_ifg_physical Summary: Created sub-functions, added data structures, improved naming and removed unnecessary code Reviewed-by: kvn, roland, rbackman

Compiled from "HelloWorld.java"
public class HelloWorld extends java.lang.Object{
    public HelloWorld();
    public static void main(java.lang.String[]);
    public native void test();
}