If "ps" fails, in many cases it prints a meaningful error message
which a user can benefit from. Let's use it.
While at it, let's use errdefs.System to classify the error,
as well as errors.Wrap.
Before:
> $ docker top $CT <any bad ps options>
> Error response from daemon: Error running ps: exit status 1
After:
> $ docker top $CT auxm
> Error response from daemon: ps: error: thread display conflicts with forest display
or
> $ docker top $CT saur
> Error response from daemon: ps: error: conflicting format options
or, if there's no meaningful error on stderr, same as before:
> $ docker top $CT 1234
> Error response from daemon: ps: exit status 1
Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>
Upstream-commit: a41328d5704b8d1adbcd099fb4bb0697060df806
Component: engine
034a285949