tests: Print errors if the status is wrong.

* tests/run-test-suite.in (run-test): If the test exits with an
unexpected status, print everything written to standard error to
make debugging easier.

tests/run-test-suite.in

@@ -198,7 +198,8 @@ output, and standard error as three values."
               (display-output stdout))
             (unless stderr-ok?
               (display "Expected stderr: ")
-              (display-output xstderr)
+              (display-output xstderr))
+            (unless (and stderr-ok? status-ok?)
               (display "Actual stderr: " )
               (display-output stderr))
             (format #t "Result: ~a~%" result)