AP_OSD: correct includes for AP_Arming change

This file was getting the copter-or-heli define from AP_Arming, which was getting it from AP_InertialSensor.  This broke when AP_Arming stopped getting AP_InertialSensor, so add the include.

Also takes the opportunity to stop including GCS.h

libraries/AP_OSD/AP_OSD_ParamScreen.cpp

@@ -26,9 +26,9 @@
 #include <AP_HAL/Util.h>
 #include <limits.h>
 #include <ctype.h>
-#include <GCS_MAVLink/GCS.h>
 #include <AP_RCMapper/AP_RCMapper.h>
 #include <AP_Arming/AP_Arming.h>
+#include <AP_Vehicle/AP_Vehicle_Type.h>
 
 extern const AP_HAL::HAL& hal;
 
@@ -629,7 +629,7 @@ void AP_OSD_ParamScreen::save_parameters()
 
 // handle OSD configuration messages
 #if HAL_GCS_ENABLED
-void AP_OSD_ParamScreen::handle_write_msg(const mavlink_osd_param_config_t& packet, const GCS_MAVLINK& link)
+void AP_OSD_ParamScreen::handle_write_msg(const mavlink_osd_param_config_t& packet, const class GCS_MAVLINK& link)
 {
     // request out of range - return an error
     if (packet.osd_index < 1 || packet.osd_index > AP_OSD_ParamScreen::NUM_PARAMS) {
@@ -642,7 +642,7 @@ void AP_OSD_ParamScreen::handle_write_msg(const mavlink_osd_param_config_t& pack
 }
 
 // handle OSD show configuration messages
-void AP_OSD_ParamScreen::handle_read_msg(const mavlink_osd_param_show_config_t& packet, const GCS_MAVLINK& link)
+void AP_OSD_ParamScreen::handle_read_msg(const mavlink_osd_param_show_config_t& packet, const class GCS_MAVLINK& link)
 {
     // request out of range - return an error
     if (packet.osd_index < 1 || packet.osd_index > AP_OSD_ParamScreen::NUM_PARAMS) {