运行
make px4_sitl jmavsim
报错
ninja: error: '../../src/modules/mavlink/mavlink/pymavlink/tools/mavgen.py', needed by 'mavlink/development/development.h', missing and no known rule to make it make: *** [Makefile:232：px4_sitl] 错误 1
原因是../../src/modules/mavlink/mavlink/pymavlink路径下为空文件夹，没有内容，解决方案是重新从Github上下载对应文件。
