review request (XS) - 7150454: add release jdk7u4 to jprt.properties

[John Coomes]

Hi,

I'd appreciate reviews of a small change to allow jprt to build
hotspot with '-release jdk7u4'.

	http://cr.openjdk.java.net/~jcoomes/7150454-jprt-jdk7u4/

Tested with 'jprt submit -release jdk7u4'.

-John