Some POSIX utilities are specified to return a specific value on error,
which is not 1. `Main::set_return_code_for_errors()` lets you set it to
that value.
By linking with LibMain, your program no longer needs to provide main().
Instead, execution begins in this function:
ErrorOr<int> serenity_main(Main::Arguments);
This allows programs that link with LibMain to use TRY() already in
their entry function, without having to do manual ErrorOr unwrapping.
This is very experimental, but it seems like a nice idea so let's try it
out. :^)
