use __ARMCC_VERSION to replace __CC_ARM

* [rtdef] rename RT_WEAK attribute as rt_weak

* [rtdef] rename RT_USED attribute as rt_used

* [rtdef] rename RT_SECTION attribute as rt_section

* [rtdef] rename ALIGN attribute as rt_align

* [legacy] add RT_USED ALIGN RT_SECTION RT_WEAK as legacy support

如果打印格式为"%02X"的数据大于0x7F,打印的数据就会在前面多出6个'F',原因详见https://blog.csdn.net/zqxwce821/article/details/53011925。
现在通过强制转换成unsigned char后，在STM32（KEIL5+C99）已测试确认能修复该问题。

* [lwip] integrate lwip porting layer

* Lwip 通用文件梳理 (#2)

* [modify] extract the common files for different version about lwip.

* [update] the initialization logic of lwIP.

* 整理源码结构

* ethernetif 头文件 ""改为<>

* 整理代码

* add macro definition "RT_USING_DEVICE_IPC".

* [update] mandatory selected "RT_USING_DEVICE_IPC".

* [modify] compile error for lost "lwip/init.h"
Co-authored-by: Nxiangxistu <52819708+xiangxistu@users.noreply.github.com>
Co-authored-by: Nliuxianliang <liuxianliang@rt-thread.com>

* [net] adjust folder structure
- 将lwip相关的文件夹，移入lwip文件夹
- Kconfig 分散到at netdev lwip sal文件夹中，使用menuconfig代替menu

AT模块在执行AT+CLOSE并返回OK后，在实际关闭前（上报URC前）仍然有
可能接收到数据。所以接收数据时需要判断状态是否为AT_SOCKET_CONNECT。

另，at_recv_notice_cb在拒绝数据包时，没有释放数据包内存，从而导致
内在泄漏。

失败现象为“找不到EAGAIN”，此问题由libc改动引发。

Revert "fix the bug that rx_notice out of sync when data received after last rt_device_read() is zero"

2、sal socket在支持多网卡时，sal_getaddrinfo从A网卡获取的地址信息，在sal_freeaddrinfo释放时必须由A网卡进行释放

fix at_client, avoid creating the same client repeatedly and prevent working exceptions and memory leaks.