Fix sys.flags to properly expose bytes_warning.

Closes issue #2790.
diff --git a/Python/sysmodule.c b/Python/sysmodule.c
index 8a1ef3c..c884250 100644
--- a/Python/sysmodule.c
+++ b/Python/sysmodule.c
@@ -1178,9 +1178,9 @@
 	flags__doc__,	/* doc */
 	flags_fields,	/* fields */
 #ifdef RISCOS
-	15
+	16
 #else
-	14
+	15
 #endif
 };