[OpenJDK 2D-Dev] RFR: 8130264 : change the mechanism by which JDK loads the platform-specific PrinterJob implementation

[Phil Race]

bug: http://cr.openjdk.java.net/~prr/8130264/
webrev: http://cr.openjdk.java.net/~prr/8130264/

Currently java launcher code embeds the name of the java.desktop 
module's PrinterJob
implementation class for each platform in a system property which is later
read by the java.desktop code to use to reflectively locate the class 
and instantiate it.

This fix removes that entirely from the launcher code and the desktop module
now looks it up internally via a simple platform proxy class.

This builds on all platforms and we rely on existing printing tests to 
verify
that we can still locate the implementation class.

The new regression test just verifies the system property name space is 
no longer polluted.
I didn't find any test (apart from this new one) that references it.

Since that system property has been around for a long time I am thinking 
I should file a CSR
to document its removal .. unless there is a concensus it is not necessary.

-phil.