`exit()` under node does not obey `EXIT_RUNTIME`

The following program will tick forever (since `EXIT_RUNTIME` defaults to 0):

```
#include
#include

int main() {
EM_ASM(
function f() { err('tick'); setTimeout(f, 1000); }
setTimeout(f, 1000);
);
return 0;
}
```

However if we change `return 0` to `exit(0)` then the program ticks forever on the web, but not under node.

Under node we see the message but the program immediately exits without ever showing a tick:

```
program exited (with status: 0), but EXIT_RUNTIME is not set, so halting
execution but not exiting the runtime or preventing further async execution
(build with EXIT_RUNTIME=1, if you want a true shutdown)
```

On the web we see the same message but we tick forever.

This is because the `exit()` calls `quit_` which calls `process['exit']`.

Is this indented behaviour? If so the message seems wrong.