Fix some memory leaks

src/hashtable.c

@@ -92,6 +92,7 @@ static void rehash(LispHashTable *ht, size_t new_size) {
             nb->value = cob->value;
         }
     }
+    lisp_free(old_data);
 }
 
 static void maybe_rehash(LispHashTable *ht) {