`emscripten_force_exit` waits for scheduled work

Example:

```c
#include
#include

static void delayedWork(void *unused) {
puts("2");
}

int main() {
puts("1");
emscripten_async_call(delayedWork, NULL, 5000);
emscripten_force_exit(0);
}
```

When executed in either Node.js or browser, you can see that it attempts to execute the scheduled work and fails on assertions because runtime counters are already zeroed:

```
> node a.out.js
1
Aborted(Assertion failed)
/home/rreverser/emscripten/a.out.js:127
throw ex;
^

RuntimeError: Aborted(Assertion failed)
at abort (/home/rreverser/emscripten/a.out.js:648:11)
at assert (/home/rreverser/emscripten/a.out.js:361:5)
at runtimeKeepalivePop (/home/rreverser/emscripten/a.out.js:1200:7)
at Timeout._onTimeout (/home/rreverser/emscripten/a.out.js:1207:9)
at listOnTimeout (node:internal/timers:573:17)
at process.processTimers (node:internal/timers:514:7)

Node.js v19.9.0
```

Additionally, in Node.js it's particularly obvious that it waits those 5 seconds for the scheduled work to finish.

I believe, based on the description, `emscripten_force_exit` should exit without waiting for any work or attempting to execute it.