RFR: 8007327: (xxs) Emit MEMORY_SIZE into spec.gmk

[Mike Duigou]

Hello all;

This is a very simple patch which causes the already calculated MEMORY_SIZE variable to be emitted into the spec.gmk where it can be used by make scripts. Generally this will be to provide a different calculation of the number of concurrent jobs.

JBSBUG: https://bugs.openjdk.java.net/browse/JDK-8007327
WEBREV: http://cr.openjdk.java.net/~mduigou/JDK-8007327/0/webrev/

Mike