8076543: Add @modules as needed to the langtools tests
Reviewed-by: jjg, shurailine

8022161: javac Null Pointer Exception in Enter.visitTopLevel
Reviewed-by: jjg, vromero, jlahoda

6960424: new option -Xpkginfo for better control of when package-info.class is generated
Reviewed-by: mcimadamore