RFR: JDK-8237914: The test-make target does not fail on test failure

[Tim Bell]

Erik:

> When running the make tests for the build itself, RunTest.gmk currently 
> does not attempt at parsing the results. Because of this, failures 
> aren't detected and so the build does not fail if a test fails. This 
> patch adds a very rudimentary parsing, defining the whole test run as 1 
> test and success/fail based on the exit code. With this, a test failure 
> will cause the top level make to exit with error. I've verified that the 
> testmake tests are still clean on all relevant platforms (as our CI 
> would have failed to notice failures for a while).
> 
> Webrev: http://cr.openjdk.java.net/~erikj/8237914/webrev.01/
> 
> Bug: https://bugs.openjdk.java.net/browse/JDK-8237914

Looks good.

Tim