Revert "Add missing break to switch."

For match_tag == SLT_Timestamp, we'd miss a match otherwise.
Add the missing /* FALLTHROUGH */

This reverts commit 97bfb002.

bin/varnishhist/varnishhist.c

@@ -268,7 +268,7 @@ accumulate(struct VSL_data *vsl, struct VSL_transaction * const pt[],
 				break;
 			case SLT_Timestamp:
 				tsp = VSL_CDATA(tr->c->rec.ptr);
-				break;
+				/* FALLTHROUGH */
 			default:
 				if (tag != match_tag)
 					break;