MINOR: checks/obj_type: Add a new object type for checks

An object type is now affected to the check structure.
diff --git a/include/types/obj_type.h b/include/types/obj_type.h
index 9410718..da3e735 100644
--- a/include/types/obj_type.h
+++ b/include/types/obj_type.h
@@ -42,6 +42,7 @@
 	OBJ_TYPE_SRVRQ,        /* object is a struct dns_srvrq */
 	OBJ_TYPE_CS,           /* object is a struct conn_stream */
 	OBJ_TYPE_STREAM,       /* object is a struct stream */
+	OBJ_TYPE_CHECK,        /* object is a struct check */
 	OBJ_TYPE_ENTRIES       /* last one : number of entries */
 } __attribute__((packed)) ;