socket_portable and bind

Since panda does using namespace std; everywhere, bare references to bind() are ambiguous with 's std::bind, and generate a compile error on some systems. Normally, I would be for ceasing use of using namespace std; in headers, but that is a large task. Until such time as that change could be made, I think everyone would be better off by explicitly referencing socket functions as members of the global scope.

I already have made a commit that does this for ::bind. Is there a reason to do so for the other functions as well?

Not a specific reason, but only to keep those api calls consistent within the file, and to preemptively disambiguate any of those other calls against client code.