MINOR: channel/stconn: Replace sc_shutr() by sc_abort()

All reference to a shutr is replaced by an abort. So sc_shutr() is renamed
sc_abort(). SC app ops functions are renamed accordingly.
diff --git a/src/cli.c b/src/cli.c
index cd1e9a8..840f775 100644
--- a/src/cli.c
+++ b/src/cli.c
@@ -2747,7 +2747,7 @@
 		pcli_write_prompt(s);
 
 		s->scb->flags |= SC_FL_NOLINGER | SC_FL_NOHALF;
-		sc_shutr(s->scb);
+		sc_abort(s->scb);
 		sc_shutw(s->scb);
 
 		/*