runner: Restore error output in the "unexpected failure" case

We accidentally lost this in
https://boringssl-review.googlesource.com/c/boringssl/+/75507

Change-Id: Ib22a68e43fd78f007e79c338127f10b575c4de7e
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/77127
Auto-Submit: David Benjamin <davidben@google.com>
Commit-Queue: Bob Beck <bbe@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Bob Beck <bbe@google.com>
diff --git a/ssl/test/runner/runner.go b/ssl/test/runner/runner.go
index 79866d9..0aa5bc3 100644
--- a/ssl/test/runner/runner.go
+++ b/ssl/test/runner/runner.go
@@ -1763,7 +1763,7 @@
 		var msg string
 		switch {
 		case failed && !test.shouldFail:
-			msg = "unexpected failure"
+			msg = fmt.Sprintf("unexpected failure\ngot:\n%s\n", got)
 		case !failed && test.shouldFail:
 			msg = fmt.Sprintf("unexpected success\nwant:\n%s\n", want)
 		case failed && !correctFailure: