用来测试手机待机情况下所能使用的最大内存量，普通用函数调用得到的剩于内存是错误的，这个通过用INT占用内存来获得可以使用的内存真正空间大小-Used to test mobile phone standby cases the maximum amount of memory can be used by the general use function calls get left in the memory is wrong, it occupied by the memory by usi