Remove dependancy of default.c on internal/object.h

We don't want the default GC to depend on Ruby internals so we can build
it as a modular GC.

Author: peterzhu2118

gc/default/default.c

@@ -28,7 +28,6 @@
 #include "ruby/util.h"
 #include "ruby/vm.h"
 #include "ruby/internal/encoding/string.h"
-#include "internal/object.h"
 #include "ccan/list/list.h"
 #include "darray.h"
 #include "gc/gc.h"
@@ -2972,7 +2971,7 @@ rb_gc_impl_shutdown_free_objects(void *objspace_ptr)
                 if (RB_BUILTIN_TYPE(vp) != T_NONE) {
                     rb_gc_obj_free_vm_weak_references(vp);
                     if (rb_gc_obj_free(objspace, vp)) {
-                        RBASIC_RESET_FLAGS(vp);
+                        RBASIC(vp)->flags = 0;
                     }
                 }
             }
@@ -3046,7 +3045,7 @@ rb_gc_impl_shutdown_call_finalizer(void *objspace_ptr)
                 if (rb_gc_shutdown_call_finalizer_p(vp)) {
                     rb_gc_obj_free_vm_weak_references(vp);
                     if (rb_gc_obj_free(objspace, vp)) {
-                        RBASIC_RESET_FLAGS(vp);
+                        RBASIC(vp)->flags = 0;
                     }
                 }
             }