import RT-Thread@9217865c without bsp, libcpu and components/net

components/libc/cplusplus/cpp11/README.md

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+# C++ 11 support for RT-Thread
+
+## Features
+
+Here are some features about rt-thread c++11 threading futures.
+
+- Atomic.
+- Conditional variables.
+- Clocks.
+- Future.
+- Mutexes.
+- Threads.
+- TLS.
+
+## How To Use
+
+Note that using C++ 11 in rt-thread requires modifying some of the files in the toolchain. Before modifying the tool, back up the tool chain.  
+
+1. Enable c++11 support
+
+   ![](figures/Snipaste_2021-09-02_16-00-09.png)
+
+2. Download toolchain GCC 10.2.1:
+
+   ```shell
+   gcc version 10.2.1 20201103 (release) (GNU Arm Embedded Toolchain 10-2020-q4-major)
+   ```
+
+3. Delete the following files:
+
+   ```shell
+   rm -f toolchain/arm-none-eabi/include/c++/10.2.1/thread
+   rm -f toolchain/arm-none-eabi/include/c++/10.2.1/mutex
+   rm -f toolchain/arm-none-eabi/include/c++/10.2.1/condition_variable
+   rm -f toolchain/arm-none-eabi/include/c++/10.2.1/future
+   rm -f toolchain/arm-none-eabi/include/pthread.h
+   ```
+
+4. Clear the contents of the following files and keep them to prevent compilation failures:
+
+   ```shell
+   toolchain/arm-none-eabi/include/sys/_pthreadtypes.h
+   ```
+   
+5. Update `rtconfig.py` file. add compilation parameters:
+
+   ```shell
+   CXXFLAGS = CFLAGS  + ' -std=c++11 -fabi-version=0 -MMD -MP -MF'
+   ```