Cygwin: default to O_BINARY in fhandler_base::reset_to_open_binmode()

This only affects the very seldom bordercase of apps calling setmode(fd,
0) on fhandlers not calling fhandler_base::set_open_status().  All
fhandlers not calling set_open_status() are binary mode only, but the
way reset_to_open_binmode worked, calling setmode(fd, 0) would have
"reset" their open flags to O_TEXT accidentally.

Signed-off-by: Corinna Vinschen <corinna@vinschen.de>

winsup/cygwin/fhandler.h

@@ -274,7 +274,8 @@ class fhandler_base
   void reset_to_open_binmode ()
   {
     set_flags ((get_flags () & ~(O_TEXT | O_BINARY))
-	       | ((open_status.wbinary || open_status.rbinary)
+	       | (((open_status.wbinset ? open_status.wbinary : 1)
+		   || (open_status.rbinset ? open_status.rbinary : 1))
 		   ? O_BINARY : O_TEXT));
   }