[9] RFR (XS) 8066507: JPRT is not capable of running jtreg tests located jdk/test

[Chris Plummer]

Please review the following fix to allow running jdk jtreg tests using 
JPRT -rtests. This is the same fix that his been in place in 
hotspot/test/Makefile for a while now, so I just copied from there to 
jdk/test/Makefile.

https://bugs.openjdk.java.net/browse/JDK-8066507
http://cr.openjdk.java.net/~cjplummer/8066507/webrev.00/

thanks,

Chris