stackctrl: Add "mp_" prefix.
diff --git a/py/obj.c b/py/obj.c
index 12d7898..3077fd2 100644
--- a/py/obj.c
+++ b/py/obj.c
@@ -61,7 +61,7 @@
 
 void mp_obj_print_helper(void (*print)(void *env, const char *fmt, ...), void *env, mp_obj_t o_in, mp_print_kind_t kind) {
     // There can be data structures nested too deep, or just recursive
-    STACK_CHECK();
+    MP_STACK_CHECK();
 #if !NDEBUG
     if (o_in == NULL) {
         print(env, "(nil)");