Mavericks java recipe?

[Daniel J. Luke]

Before I do more work on #41378, I figured that I'd ask and see if anyone has worked up a nice recipe for detecting a java install on Mavericks yet?

I'd like the subversion-javahlbindings port to be able to warn people and exit early if the appropriate java bits aren't present and I imagine other ports might want the same thing (possibly a candidate for a portgroup, too).

--
Daniel J. Luke                                                                   
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