RT-Thread/rt-thread: https://github.com/RT-Thread/rt-thread.git @ beb2f046c41af176076c4fbda68291c426075068

Bernard Xiong beb2f046c4 Merge pull request #4649 from mysterywolf/libc2		4 rokov pred
..
none-gcc	cb7fa8fcea implement pid_t gettid(void)	4 rokov pred
sys	1627597fcc remove _TIMESPEC_DEFINED	4 rokov pred
SConscript	ae66d82624 update sconscript	4 rokov pred
dirent.h	f9ba41f4c2 更改libc目录为common 以及 none-gcc	4 rokov pred
readme.md	f9ba41f4c2 更改libc目录为common 以及 none-gcc	4 rokov pred
stdlib.c	3c05a4e719 [compoenets] auto & manual formatted	4 rokov pred
termios.h	3c05a4e719 [compoenets] auto & manual formatted	4 rokov pred
time.c	82f2d8e53d time.c 删除函数名与括号之间的空格	4 rokov pred
unistd.c	19347ed454 [libc][unistd] 完善isatty()	4 rokov pred

Attentions

This folder is "common" for all toolchains.
If you want to add new .c files, please do not forget to fix SConscript file too. eg:
```
if GetDepend('RT_USING_POSIX') == False:
    SrcRemove(src, ['unistd.c'])
```