MINOR: stream-int/conn-stream: Move si_shut* and si_chk* in conn-stream scope

si_shutr(), si_shutw(), si_chk_rcv() and si_chk_snd() are moved in the
conn-stream scope and renamed, respectively, cs_shutr(), cs_shutw(),
cs_chk_rcv(), cs_chk_snd() and manipulate a conn-stream instead of a
stream-interface.
diff --git a/src/peers.c b/src/peers.c
index d77010d..a6544a2 100644
--- a/src/peers.c
+++ b/src/peers.c
@@ -3099,8 +3099,8 @@
 					HA_SPIN_UNLOCK(PEER_LOCK, &curpeer->lock);
 					curpeer = NULL;
 				}
-				si_shutw(cs->si);
-				si_shutr(cs->si);
+				cs_shutw(cs);
+				cs_shutr(cs);
 				cs_ic(cs)->flags |= CF_READ_NULL;
 				goto out;
 			}