message: logging: added Android printfs
diff: #define UNUSED(x) (void)(x)
  -#include <iostream>
  #include <sstream>
  #include <chrono>
  +#if ANDROID
  +#include <android/log.h>
  +#else
  +#include <iostream>
  +#endif
  +
  namespace dronelink {
  class Debug
  @@ -23,7 +28,11 @@ public:
  ~Debug()
  {
  +#if ANDROID
  + __android_log_print(ANDROID_LOG_DEBUG, "DroneLink", "%s", _s.str().c_str());
  +#else
  std::cout << _s.str() << std::endl;
  +#endif
  }
  private:
  