javac update

[Jonathan Gibbons]

I've managed to merge my langtools repo for "compiling langtools against 
jdk7 stubs" with a "Jigsaw langtools". Slight hiccup: Mark has been 
using the diamond operator in the new Jigsaw code, which confused my 
stub generator for a while.

Can someone give me a brief recipe on setting up a simple module 
library, sufficient for testing the upcoming new -L switch in the compiler?

-- Jon