It is unsafe. But it would be safe if these two lines were swapped:

    count++;
    pthread_mutex_lock(&m);

since the reader already holds the mutex while reading `count`.

Do a PR or equivalent?

Friendly reminder that not everyone is in a position where they can create pull requests against random projects: they might not have time, or clearance from their company's legal department, or…

???

Note it was a question. As you mention, not everyone can do so (etc).

The question looked like "why are aren't you making a PR for this".

The second example is also leaking memory.