Most changes are around user and group management, which are exposed in
the Android NDK differently than other Unices.
We require version 30 for memfd_create, version 28 for posix_spawn, and
so on. It's possible a shim for memfd_create could be used, but since
Google is mandating new apps use API level 30 as of Nov 2022, this seems
suitable.
This hides the method Group::add_group() on both MacOS and OpenBSD since
the function putgrent(), which is essential for add_group() to work, is
not available on these OSes.
This adds the Core::Group C++ abstraction to ease interaction with the
group entry database, as well as represent the Group entry.
Core::Group abstraction currently contains the following functionality:
- Add a group entry - 'Core::Group::add_group()'
