MINOR: stconn: Rename SC_FL_SHUTW in SC_FL_SHUT_DONE

Here again, it is just a flag renaming. In SC flags, there is no longer
shutdown for writes but shutdowns.
diff --git a/src/ssl_crtlist.c b/src/ssl_crtlist.c
index f74f43a..5296118 100644
--- a/src/ssl_crtlist.c
+++ b/src/ssl_crtlist.c
@@ -1117,7 +1117,7 @@
 	 * created.
 	 */
 	/* FIXME: Don't watch the other side !*/
-	if (unlikely(sc_opposite(sc)->flags & SC_FL_SHUTW))
+	if (unlikely(sc_opposite(sc)->flags & SC_FL_SHUT_DONE))
 		goto end;
 
 	switch (ctx->state) {