[OpenJDK 2D-Dev] RFR: Fix for 8032693 : javax.print.PrintService does not find any CUPS-Printers on Linux

[Phil Race]

http://cr.openjdk.java.net/~prr/8032693/

This is a fix for https://bugs.openjdk.java.net/browse/JDK-8032693

It was introduced by the JDK 8 b115 fix for 
https://bugs.openjdk.java.net/browse/JDK-8022536

The root of the issue is that if you do not have a default printer set 
in CUPS then
we get an NPE at line 635 (original file) of UnixPrintServiceLookup.java 
de-referencing
the array  returned from CUPSPrinter.getDefaultPrinter().

This caused a failure not just locating the default but *any* printer 
because
the NPE went all the way back up to javax.print implementation where it 
calls
getPrintServices()

Really preventing that NPE from happening is all there is to the fix
But for good measure I
1) Catch such an exception inside refreshServices() so we can continue on
2) Fix the usage of device-uri (should be printer-uri-supported)
3) Add lots more debugging to make it easier to get to the bottom of 
future problems.

I'm pretty confident in this fix since I was able to reproduce the problem
by updating CUPS so I had no default and this cures it.

I've added a regression test as best I can. Unless you have printers, but
have also no default printer its going to pass regardless.

-phil