repl: better SIGINT handling behavior

Before:

☮ ~ (master) ⚡ node
> asdf
(^C again to quit)
> sdcasd☮ ~ (master) ⚡

Now:

☮ ~/node (repl) ⚡ ./node
> asfs
> sda
>
(^C again to quit)
> scdsdc
> sdcsdc
>
(^C again to quit)
> sdc
>
(^C again to quit)
>
☮ ~/node (repl) ⚡

^ note that each new line above is a ctrl+c sequence