[patch] prefork: support --listen-address for consistency with forkserver

forkserver uses --listen-address to specify the listening socket address, while prefork uses --interface. Add the former as an alias for the latter, for consistency ease of integration. The two still aren't commandline-compatible, but they're fairly close. Can also be pulled from

Re: [patch] prefork: support --listen-address for consistency with forkserver

Thanks, I put it in my repository as e8ee72a. - ask