RFR (XS): 8167354: Missing jtreg output when run using langtools makefiles

[Marcus Larsson]

Hi,

Please review the following small patch to make the output from jtreg 
for langtools testing through make to be saved in output.txt, just like 
in other repos.

Webrev:
http://cr.openjdk.java.net/~mlarsson/8167354/webrev.00

Issue:
https://bugs.openjdk.java.net/browse/JDK-8167354

Thanks,
Marcus