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/applet.c b/src/applet.c
index d39327e..37e642f 100644
--- a/src/applet.c
+++ b/src/applet.c
@@ -114,7 +114,7 @@
 	/* If a frontend appctx is attached to a stream connector, release the stream
 	 * instead of the appctx.
 	 */
-	if (!se_fl_test(appctx->sedesc, SE_FL_ORPHAN) && !(appctx_cs(appctx)->flags & CS_FL_ISBACK)) {
+	if (!se_fl_test(appctx->sedesc, SE_FL_ORPHAN) && !(appctx_cs(appctx)->flags & SC_FL_ISBACK)) {
 		stream_free(appctx_strm(appctx));
 		return;
 	}