add extra tld==NULL check for free's after a thread has terminated (pr #1289)

Author: daanx

src/free.c

@@ -322,7 +322,7 @@ static mi_decl_noinline bool mi_abandoned_page_try_reclaim(mi_page_t* page, long
 
   // get our theap 
   mi_theap_t* const theap = _mi_page_associated_theap_peek(page);
-  if (theap==NULL || !theap->allow_page_reclaim) return false;
+  if (theap==NULL || theap->tld==NULL || !theap->allow_page_reclaim) return false;  // see issue #1289
 
   // todo: cache `is_in_threadpool` and `exclusive_arena` directly in the theap for performance?
   // set max_reclaim limit

src/init.c

@@ -426,7 +426,7 @@ mi_subproc_t* _mi_subproc(void) {
   //       on such systems we can check for this with the _mi_prim_get_default_theap as those are protected (by being
   //       stored in a TLS slot for example)
   mi_theap_t* theap = _mi_theap_default();
-  if (theap == NULL || theap->tld == NULL) {
+  if (theap == NULL || theap->tld == NULL) {  // see issue #1289
     return _mi_subproc_main();
   }
   else {