fix memory leak in the C code (#1203)

* fix memory leak when size(deque) == 1

* fix memory leak

codes/c/chapter_hashing/hash_map_open_addressing.c

@@ -49,6 +49,9 @@ void delHashMapOpenAddressing(HashMapOpenAddressing *hashMap) {
             free(pair);
         }
     }
+    free(hashMap->buckets);
+    free(hashMap->TOMBSTONE);
+    free(hashMap);
 }
 
 /* 哈希函数 */