Fixed possible segfault in swoole_table

The `memory_size` in `swTable_create` should be:

```c
size_t memory_size = (row_num * row_memory_size) + (table->size * sizeof(swTableRow *))  + sizeof(swMemoryPool) + sizeof(swFixedPool) + ((row_num - table->size) * sizeof(swFixedPool_slice));
```

otherwise, `swFixedPool_init()` may override not allocated memory and cause segfault.