message: core: fix Android build
diff: #pragma once
  #include <sstream>
  +#include "global_include.h"
  #if ANDROID
  #include <android/log.h>
  @@ -80,6 +81,8 @@ public:
  __android_log_print(ANDROID_LOG_ERROR, "DroneCore", "%s", _s.str().c_str());
  break;
  }
  + UNUSED(_caller_filename);
  + UNUSED(_caller_filenumber);
  #else
  // Time output taken from:
  