Add `GC.auto_compact= true/false` and `GC.auto_compact`

* `GC.auto_compact=`, `GC.auto_compact` can be used to control when
  compaction runs.  Setting `auto_compact=` to true will cause
  compaction to occurr duing major collections.  At the moment,
  compaction adds significant overhead to major collections, so please
  test first!

[Feature #17176]

1 files changed, 1 insertions, 0 deletions

diff --git a/internal/vm.h b/internal/vm.h
index 1ae2ba064a..246a42a793 100644
--- a/internal/vm.h
+++ b/internal/vm.h
@@ -47,6 +47,7 @@ rb_serial_t rb_next_class_serial(void);
 /* vm.c */
 VALUE rb_obj_is_thread(VALUE obj);
 void rb_vm_mark(void *ptr);
+void rb_vm_each_stack_value(void *ptr, void (*cb)(VALUE, void*), void *ctx);
 PUREFUNC(VALUE rb_vm_top_self(void));
 void rb_vm_inc_const_missing_count(void);
 const void **rb_vm_get_insns_address_table(void);