Improve messages in case of system exit. This prints a better set of error messages in case someone calls `os._exit()` or in C code `exit()` is used.

Resolves #3486.

- [x] Add a [CHANGELOG](https://github.com/pyodide/pyodide/blob/main/docs/project/changelog.md) entry

from .ffi import IN_BROWSER

__all__ = ["IN_BROWSER"]

from .ffi import IN_BROWSER

__all__ = ["IN_BROWSER"]
