CLEANUP: stconn: rename cs_{shut,chk}* to sc_*

This applies the following renaming:

cs_shutr() -> sc_shutr()
cs_shutw() -> sc_shutw()
cs_chk_rcv() -> sc_chk_rcv()
cs_chk_snd() -> sc_chk_snd()
cs_must_kill_conn() -> sc_must_kill_conn()
diff --git a/src/tcp_rules.c b/src/tcp_rules.c
index f9656c0..8b9aa76 100644
--- a/src/tcp_rules.c
+++ b/src/tcp_rules.c
@@ -254,7 +254,7 @@
 		_HA_ATOMIC_INC(&sess->listener->counters->failed_req);
 
  reject:
-	cs_must_kill_conn(chn_prod(req));
+	sc_must_kill_conn(chn_prod(req));
 	channel_abort(req);
 	channel_abort(&s->res);
 
@@ -392,9 +392,9 @@
 			}
 			else if (rule->action == ACT_TCP_CLOSE) {
 				chn_prod(rep)->flags |= SC_FL_NOLINGER | SC_FL_NOHALF;
-				cs_must_kill_conn(chn_prod(rep));
-				cs_shutr(chn_prod(rep));
-				cs_shutw(chn_prod(rep));
+				sc_must_kill_conn(chn_prod(rep));
+				sc_shutr(chn_prod(rep));
+				sc_shutw(chn_prod(rep));
 				s->last_rule_file = rule->conf.file;
 				s->last_rule_line = rule->conf.line;
 				goto end;
@@ -451,7 +451,7 @@
 		_HA_ATOMIC_INC(&__objt_server(s->target)->counters.failed_resp);
 
  reject:
-	cs_must_kill_conn(chn_prod(rep));
+	sc_must_kill_conn(chn_prod(rep));
 	channel_abort(rep);
 	channel_abort(&s->req);