Failpoint is used to control the fail during API call when testing, especially
the API is complicated like CRI-RunPodSandbox. It can help us to test
the unexpected behavior without mock. The control design is based on freebsd
fail(9), but simpler.
REF: https://www.freebsd.org/cgi/man.cgi?query=fail&sektion=9&apropos=0&manpath=FreeBSD%2B10.0-RELEASE
Signed-off-by: Wei Fu <fuweid89@gmail.com>
