kunit: kunit_tool: Fix invalid result when build fails

When separating out different phases of running tests[1]
(build/exec/parse/etc), the format of the KunitResult tuple changed
(adding an elapsed_time variable). This is not populated during a build
failure, causing kunit.py to crash.

This fixes [1] to probably populate the result variable, causing a
failing build to be reported properly.

[1]:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=45ba7a893ad89114e773b3dc32f6431354c465d6

Signed-off-by: David Gow <davidgow@google.com>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Tested-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: Shuah Khan <skhan@linuxfoundation.org>

tools/testing/kunit/kunit.py

@@ -82,7 +82,9 @@ def build_tests(linux: kunit_kernel.LinuxSourceTree,
 					request.make_options)
 	build_end = time.time()
 	if not success:
-		return KunitResult(KunitStatus.BUILD_FAILURE, 'could not build kernel')
+		return KunitResult(KunitStatus.BUILD_FAILURE,
+				   'could not build kernel',
+				   build_end - build_start)
 	if not success:
 		return KunitResult(KunitStatus.BUILD_FAILURE,
 				   'could not build kernel',