Review Request: 8007275: build-infra: Create final-images target

[Erik Joelsson]

Open part of this review.

Adding a target "final-images" which copies the images to use to the 
same location, regardless of platform. For OpenJDK, the only problem 
this solves is the overlay-images on Solaris 64bit, which have a 
different directory name to the normal images. This target is separate 
from the all and default targets and must be explicitly called, so it 
shouldn't bother anyone who doesn't want to use it.

I put it in Jprt.gmk, part because it shares logic with the jprt 
specific bundles target but also because like jprt it's sort of Oracle 
specific.

http://cr.openjdk.java.net/~erikj/8007275/webrev.root.01/

/Erik