SITL: include stdio for some printfs

libraries/SITL/SIM_Sprayer.cpp

@@ -20,6 +20,8 @@
 #include "AP_HAL/AP_HAL.h"
 #include "AP_Math/AP_Math.h"
 
+#include <stdio.h>
+
 using namespace SITL;
 
 // table of user settable parameters