The exit() libc function already accepted an integer, but didn't pass it on to the kernel since we had no mechanism for it to do that.
Now, the kernel stores a task's exit status to display it later (and in the future, return it to userspace via wait()/waitpid())
This struct allows us to keep track of what memory is used by the loaded executable. For some reason, freeing this memory when the task exits triggers a kernel page fault, so I'm not doing that right now.
