javac support for -modulepath

[Mark Reinhold]

Jon -- How close are you to having a javac that supports the new
-modulepath option, and the corresponding modularized output
directory, proposed in the slides that you and Alex put together?

Is this something that can be finished independently of hooking up
javac itself to the module system?

If support for -modulepath will come later rather than sooner then
for testing purposes I can hack up a temporary jmod subcommand to
convert the current output-directory format to the new one, but if
you can get this done sooner then I won't bother.

- Mark