Java: help optimizer in build_class_init

[Alexandre Petit-Bianco]

Jeff Sturm writes:

> and the following test can be optimized away, yielding slightly
> smaller/faster code.

This patch sounds good (besides reading it, I also ran tests on it.)

> Tested on 3.0 branch.

I'm not sure this should go in the branch as it doesn't really fall in
the category of things we're looking after as far as 3.0 is
concerned. On the other hand, it's an obvious fix with nice
benefits. What are people at large thinking about it?

./A