`--json` incorrect output

[1zumiSagiri]

In the JSON output, success actually refers to the total number of test cases.

{
  "success": 3,
  "failures": 1,
  "time": 0.000047
}

To reproduce the error:

git clone https://github.com/mirage/alcotest.git
cd alcotest
opam install --deps-only .
dune exec ./examples/bad/bad.exe
dune exec ./examples/bad/bad.exe -- --json

The first exec output

alcotest % dune exec ./examples/bad/bad.exe 
Testing `First suite'.                

> [FAIL]        to_test          0   capitalise.
  [FAIL]        to_test          1   double all.
...
Full test results in `~/alcotest/_build/_tests/First suite'.
2 failures! in 0.000s. 2 tests run.Forging ahead regardless!

Testing `Second suite'.

  [OK]          Ωèone          0   Passing test 1.
> [FAIL]        Ωèone          1   Failing test.
  [OK]          Ωèone          2   Passing test 2.
...
Full test results in `~/alcotest/_build/_tests/Second suite'.
1 failure! in 0.000s. 3 tests run.
Fatal error: exception Alcotest_engine__Core.Make(P)(M).Test_error

The json exec output:

alcotest %  dune exec ./examples/bad/bad.exe -- --json 
Testing `First suite'.               
This run has ID `FSES0VEN'.

Forging ahead regardless!
{
  "success": 2,
  "failures": 2,
  "time": 0.000123
}
Testing `Second suite'.
This run has ID `S6H3PB7T'.

{
  "success": 3,
  "failures": 1,
  "time": 0.000065
}
Fatal error: exception Alcotest_engine__Core.Make(P)(M).Test_error