selftests/nolibc: report: print a summarized test status

one of the test status: success, warning and failure is printed to
summarize the passed, skipped and failed values.

- "success" means no skipped and no failed.
- "warning" means has at least one skipped and no failed.
- "failure" means all tests are failed.

Suggested-by: Willy Tarreau <w@1wt.eu>
Link: https://lore.kernel.org/lkml/20230702164358.GB16233@1wt.eu/


Signed-off-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>