MINOR: channel/stconn: Replace sc_shutw() by sc_shutdown()

All reference to a shutw is replaced by an abort. So sc_shutw() is renamed
sc_shutdown(). SC app ops functions are renamed accordingly.
diff --git a/src/cli.c b/src/cli.c
index 55a825a..bcb4ce7 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -2748,7 +2748,7 @@
 
 		s->scb->flags |= SC_FL_NOLINGER | SC_FL_NOHALF;
 		sc_abort(s->scb);
-		sc_shutw(s->scb);
+		sc_shutdown(s->scb);
 
 		/*
 		 * starting from there this the same code as