langtools: no more warnings

[Jonathan Gibbons]

For those that didn't notice the fine print, a recent push to the  
langtools repository [1]  finally raised the quality bar on the  
langtools repository.
That push fixed (or suppressed) the remaining outstanding warnings in  
the repository, and enabled -Xlint:all -Werror.

Now, if only the other repositories could do the same...

-- Jon

[1] http://mail.openjdk.java.net/pipermail/compiler-dev/2009-January/000873.html