AP_HAL: fix example sketches

libraries/AP_HAL/examples/Printf/Printf.pde

@@ -29,6 +29,7 @@
 #include <AP_NavEKF.h>
 #include <AP_Rally.h>
 #include <AP_BattMonitor.h>
+#include <AP_RangeFinder.h>
 
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 

libraries/AP_HAL/examples/RCInput/RCInput.pde

@@ -34,6 +34,7 @@
 #include <AP_Scheduler.h>
 #include <UARTDriver.h>
 #include <AP_BattMonitor.h>
+#include <AP_RangeFinder.h>
 
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 

libraries/AP_HAL/examples/RCInputToRCOutput/RCInputToRCOutput.pde

@@ -37,6 +37,7 @@
 #include <AP_Scheduler.h>
 #include <UARTDriver.h>
 #include <AP_BattMonitor.h>
+#include <AP_RangeFinder.h>
 
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 

libraries/AP_HAL/examples/RCOutput/RCOutput.pde

@@ -34,6 +34,7 @@
 #include <AP_Scheduler.h>
 #include <UARTDriver.h>
 #include <AP_BattMonitor.h>
+#include <AP_RangeFinder.h>
 
 const AP_HAL::HAL& hal = AP_HAL_BOARD_DRIVER;
 

libraries/AP_HAL/examples/UART_test/UART_test.pde

@@ -34,6 +34,7 @@
 #include <AP_Scheduler.h>
 #include <UARTDriver.h>
 #include <AP_BattMonitor.h>
+#include <AP_RangeFinder.h>
 
 #if HAL_OS_POSIX_IO
 #include <stdio.h>