Maelstrom Worker Child

This is a small library that is only intended to be used by the maelstrom-worker. It is its own library so it can be no_std and we can ensure that it doesn't take any undesired dependencies.

This library is intended to be used in the child processes after a clone syscall in potentially-multithreaded processes. The child process in this case is very limited in what it can do without potentially blocking forever. For example, allocations are disallowed. This library just executes a series of syscalls, the last of which should be execve.

For more information, see the Maelstrom project on GitHub.