Use a socket, not pipe, for STDIN emulation in fselect

Using a TCP connected socket allows us to use a single select call instead of
interrupting it every 125ms to poll the stdin-pipe.

nbase/nbase_winunix.h

@@ -192,6 +192,5 @@ Nbase that legitimately use ENOENT for file operations.
 typedef unsigned short u_short_t;
 
 int win_stdin_start_thread(void);
-int win_stdin_ready(void);
 
 #endif /* NBASE_WINUNIX_H */