DOS targets do have setmode().

lib/config.dos

@@ -39,6 +39,7 @@
 #define HAVE_SEND              1
 #define HAVE_SETJMP_H          1
 #define HAVE_SETLOCALE         1
+#define HAVE_SETMODE           1
 #define HAVE_SIGNAL            1
 #define HAVE_SOCKET            1
 #define HAVE_SPNEGO            1