VSI submission: redirect terminal input through socket

This is needed, because on VMS, select() can only be used on sockets.  being
able to use select() on all kinds of file descriptors is unique to Unix.

So, the solution for VMS is to create a layer that translates input from
standard input to socket communication.

Reviewed-by: Andy Polyakov <appro@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>