MINOR: conn-stream/connection: Move SHR/SHW modes in the connection scope

These flags only concerns the connection part. In addition, it is required
for a next commit, to avoid circular deps. Thus CS_SHR_* and CS_SHW_* were
renamed with the "CO_" prefix.
diff --git a/src/stream_interface.c b/src/stream_interface.c
index ca7c616..139b654 100644
--- a/src/stream_interface.c
+++ b/src/stream_interface.c
@@ -1065,7 +1065,7 @@
 			 * option abortonclose. No need for the TLS layer to try to
 			 * emit a shutdown message.
 			 */
-			cs_shutw(cs, CS_SHW_SILENT);
+			cs_shutw(cs, CO_SHW_SILENT);
 		}
 		else {
 			/* clean data-layer shutdown. This only happens on the
@@ -1074,7 +1074,7 @@
 			 * while option abortonclose is set. We want the TLS
 			 * layer to try to signal it to the peer before we close.
 			 */
-			cs_shutw(cs, CS_SHW_NORMAL);
+			cs_shutw(cs, CO_SHW_NORMAL);
 
 			if (!(ic->flags & (CF_SHUTR|CF_DONT_READ)))
 				return;
@@ -1569,7 +1569,7 @@
 	if (cs->flags & CS_FL_NOHALF) {
 		/* we want to immediately forward this close to the write side */
 		/* force flag on ssl to keep stream in cache */
-		cs_shutw(cs, CS_SHW_SILENT);
+		cs_shutw(cs, CO_SHW_SILENT);
 		goto do_close;
 	}