[DeviceDriver] Change the special device commands form 0x1X to 0x2X. It will avoid same of general device commands.

[DeviceDriver][RTC] Remove RT_DEVICE_CTRL_RTC_GET_TIME_US and RT_DEVICE_CTRL_RTC_SET_TIME_US. Add RT_DEVICE_CTRL_RTC_GET_TIMEVAL and RT_DEVICE_CTRL_RTC_SET_TIMEVAL. The RT_DEVICE_CTRL_RTC_GET_TIMEVAL cmd can get second time and microsecond time.

[kernel] rtthread.h 增加#ifdef RT_USING_HEAP 预编译

[update] support armclang

[libc]新建gcc文件夹，将newlib和partical文件夹并入

[update] RT-Thread Robot automatic submission

[bsp] Fix missing header file applications in ls2k

[libc][keil][iar] 支持system函数

[update] enable asctime_r function parameter legal.

[libc标准化][syscall]移除libc_stdio_read/write函数，优化syscall

Verify the driver in the BSP of the ART-PI main branch of rtthread.

[libc标准化]脱敏dfs_select.h 由标准sys/select.h代替

优化memheap内存管理：1.自动多块粘合可配置；

[libc]在开启libc后依然保持RT_LIBC_USING_TIME定义存在

[bsp][simulator] 消除大部分编译错误

support ch32f10x pwm driver.

[bsp][mm32f327]修复.ignore_format路径错误

修正了bsp/hc32f4a0的scons构建脚本里的语法错误

Merge AArch64 libcpu and add some drivers for their bsps

[fatfs] 修改互斥保护超时时间, 并将超时时间改为Kconfig可配置

[libc][newlib] 优化syscall 重构_libc_init_array 防止gcc下芯片无法启动