Revert "Added experimental feature NEW_KEYBOARD_HIT."

This reverts commit bc65112ce0.

sys/winnt/nttty.c

@@ -398,12 +398,10 @@ int mode; // unused
 {
     DWORD cmode;
 
-#ifndef NEW_KEYBOARD_HIT
     /* Initialize the function pointer that points to
      * the kbhit() equivalent, in this TTY case nttty_kbhit()
      */
     nt_kbhit = nttty_kbhit;
-#endif
 
     if (!SetConsoleCtrlHandler((PHANDLER_ROUTINE) CtrlHandler, TRUE)) {
         /* Unable to set control handler */
@@ -438,19 +436,11 @@ int portdebug;
     return ch;
 }
 
-#ifndef NEW_KEYBOARD_HIT
 int
 nttty_kbhit()
 {
     return keyboard_handler.pNHkbhit(console.hConIn, &ir);
 }
-#else
-boolean
-tkbhit()
-{
-    return keyboard_handler.pNHkbhit(console.hConIn, &ir) != 0;
-}
-#endif
 
 int
 tgetch()