I need wait and waitpid in posix88::unistd

[ashleysommer]

Just wondering if you can update this lib to rust @ commit a5cac55be451a32a5956339009c49ac4fcaaef5c, this introduces definitions for wait() and waitpid() into libstd::funcs::posix88::unistd that I need for a project I am working on.

Thanks.