[Libguestfs] [PATCH] java: Rename JNI target, use JNI_INSTALL_DIR as provided through configure

[Hilko Bengen]

* Matthew Booth:

> so this looks like a no-op in the default case. ACK.

I just noticed that the change is not enough, I'll need to do another
test and post a follow-up patch later.

-Hilko