Set the llvm standard output stream to be unbuffered. (#678)

This is particularly useful for the simulation when invokved
inside Eclipse.  Otherwise, you won't see the robot starting
message.

hal/src/main/native/athena/HAL.cpp

@@ -342,6 +342,7 @@ HAL_Bool HAL_Initialize(int32_t timeout, int32_t mode) {
 
   setlinebuf(stdin);
   setlinebuf(stdout);
+  llvm::outs().SetUnbuffered();
 
   prctl(PR_SET_PDEATHSIG, SIGTERM);