rec: Don't mix time() and gettimeofday() in our unit tests

rec: Don't mix time() and gettimeofday() in our unit tests

It turns out that, at least on Linux, doing

```
struct timeval now;
gettimeofday(&now, nullptr);
now.tv_sec - time(nullptr);
```

might be 1, without the time actually going backward. So let's just
be consistent in our calls and we should far less false positive
during our tests.