[PATCH 0/6] MR5993: Cmd engine rewrite (part XV)

[eric pouech (＠epo)]

This is part XV of cmd engine rewrite.

This MR deals with returning the proper success/failure
return code for POPD and RMDIR.

However, these commands never set ERRORLEVEL (all the
commands we've handled so far always set ERRORLEVEL in
case of failure, and some reset ERRORLEVEL in case of
successs).

So this MR on top of returning the expected success/failure
return code for these two commands, also:
- extend tests to show that ERRORLEVEL isn't set
- tweak internal call path to better handle return code
  vs ERRORLEVEL.