Expose RVALUE_OLD_AGE in GC::INTERNAL_CONSTANTS

gc.c

@@ -13907,6 +13907,7 @@ Init_GC(void)
     rb_hash_aset(gc_constants, ID2SYM(rb_intern("HEAP_PAGE_SIZE")), SIZET2NUM(HEAP_PAGE_SIZE));
     rb_hash_aset(gc_constants, ID2SYM(rb_intern("SIZE_POOL_COUNT")), LONG2FIX(SIZE_POOL_COUNT));
     rb_hash_aset(gc_constants, ID2SYM(rb_intern("RVARGC_MAX_ALLOCATE_SIZE")), LONG2FIX(size_pool_slot_size(SIZE_POOL_COUNT - 1)));
+    rb_hash_aset(gc_constants, ID2SYM(rb_intern("RVALUE_OLD_AGE")), LONG2FIX(RVALUE_OLD_AGE));
     if (RB_BUG_INSTEAD_OF_RB_MEMERROR+0) {
         rb_hash_aset(gc_constants, ID2SYM(rb_intern("RB_BUG_INSTEAD_OF_RB_MEMERROR")), Qtrue);
     }