CLEANUP: stconn: tree-wide rename stream connector flags CS_FL_* to SC_FL_*

This follows the natural naming. There are roughly 100 changes, all
totally trivial.
diff --git a/src/dns.c b/src/dns.c
index 4fea59c..cf61d17 100644
--- a/src/dns.c
+++ b/src/dns.c
@@ -829,7 +829,7 @@
 
 	s = appctx_strm(appctx);
 	s->scb->dst = addr;
-	s->scb->flags |= CS_FL_NOLINGER;
+	s->scb->flags |= SC_FL_NOLINGER;
 	s->target = &ds->dss->srv->obj_type;
 	s->flags = SF_ASSIGNED;