- remove function prototype for shared memory (no more used), and VIO
members that are unused
- Do not call DisconnectNamedPipe on pipe handle. CloseHandle() is enough.
Fix mismerged code from 5.6 (named-pipe related). viopipe.c, which was introduced in 5.6 is now copied almost identically into 10.0
The unused vio::pipe_overlapped is removed.