RFR: JDK-8224011: Failure handling in ExecuteWithLog fails in run-test-prebuilt

[Tim Bell]

Erik:

> When running tests using "make run-test-prebuilt", we bypass a lot of
> Init.gmk. One of the things we skip is initialization of the
> make-support/failure-logs dir. This causes make to print errors about
> failing to copy files into that directory if for example the AOT
> compilation fails, partly hiding the original error. This change simply
> adds a MakeDir on that directory as part of the RunTestPrebuilt.gmk
> bootstrap.
>
> Bug: https://bugs.openjdk.java.net/browse/JDK-8224011
>
> Webrev: http://cr.openjdk.java.net/~erikj/8224011/webrev.01/index.html

Looks good.

> (The empty change in RunTests.gmk was a trailing tab that my Emacs
> thoroughly disliked, so including that here too.)

Thanks for fixing that also.

Tim