MINOR: stats admin: reduce memcmp()/strcmp() calls on status codes

MINOR: stats admin: reduce memcmp()/strcmp() calls on status codes

memcmp()/strcmp() calls were needed in different parts of code to determine
the status code. Each new status code introduces new calls, which can become
inefficient and source of bugs.
This patch reorganizes the code to rely on a numeric status code internally
and to be hopefully more generic.