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.
This creates an error that contains the name of the syscall that failed.
This allows error handlers to print out the name of the call if they
want to. :^)
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. :^)
