sys.C is big and has a number of functionally separate components.
break sys.C into a number of smaller files to make it easier to maintain and to separate funtionality.
Historically, the main work item was fixing jconfigure to make it trivial to change/augment the number of files. The actual decomposition of sys.C shouldn't be that hard. I haven't looked to see if this is trivial or hard in the new ant-based build system. I'm guessing it will be easier though...