RFR: JDK-8185928: Generate OpenJDK builds for Mac platform JDK 9.0.3 and beyond in Mach 5

[Erik Joelsson]

This change adds configuration necessary for our internal distributed 
build system to store builds of OpenJDK on Macosx. This is intended for 
JDK 10.

Bug: https://bugs.openjdk.java.net/browse/JDK-8185928

Webrev: http://cr.openjdk.java.net/~erikj/8185928/webrev.01/

/Erik