enable double free and heap corruption detection in debug mode

src/init.c

@@ -15,14 +15,14 @@ const mi_page_t _mi_page_empty = {
   0, false, false, false, false, 0, 0,
   { 0 }, false,
   NULL,    // free
-  #if MI_SECURE
+  #if MI_ENCODE_FREELIST
   0,
   #endif
   0,       // used
   NULL, 
   ATOMIC_VAR_INIT(0), ATOMIC_VAR_INIT(0),
   0, NULL, NULL, NULL
-  #if (MI_INTPTR_SIZE==8 && MI_SECURE>0) || (MI_INTPTR_SIZE==4 && MI_SECURE==0)
+  #if (MI_INTPTR_SIZE==8 && defined(MI_ENCODE_FREELIST)) || (MI_INTPTR_SIZE==4 && !defined(MI_ENCODE_FREELIST))
   , { NULL } // padding
   #endif
 };