Fix -Wundef warnings due to use of unguarded SDL_JOYSTICK_XINPUT

src/joystick/SDL_gamepad.c

@@ -814,7 +814,7 @@ static GamepadMapping_t *SDL_PrivateGetGamepadMappingForGUID(SDL_JoystickGUID gu
         }
     }
 
-#if SDL_JOYSTICK_XINPUT
+#ifdef SDL_JOYSTICK_XINPUT
     if (SDL_IsJoystickXInput(guid)) {
         /* This is an XInput device */
         return s_pXInputMapping;

src/joystick/SDL_gamepad_db.h

@@ -29,7 +29,7 @@
    Alternatively, you can use the app located in test/controllermap
  */
 static const char *s_GamepadMappings[] = {
-#if SDL_JOYSTICK_XINPUT
+#ifdef SDL_JOYSTICK_XINPUT
     "xinput,XInput Controller,a:b0,b:b1,back:b6,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,dpup:h0.1,guide:b10,leftshoulder:b4,leftstick:b8,lefttrigger:a2,leftx:a0,lefty:a1,rightshoulder:b5,rightstick:b9,righttrigger:a5,rightx:a3,righty:a4,start:b7,x:b2,y:b3,",
 #endif
 #if SDL_JOYSTICK_WGI

src/joystick/windows/SDL_windowsjoystick.c

@@ -345,7 +345,7 @@ static SDL_DeviceNotificationData s_notification_data;
 /* Function/thread to scan the system for joysticks. */
 static int SDLCALL SDL_JoystickThread(void *_data)
 {
-#if SDL_JOYSTICK_XINPUT
+#ifdef SDL_JOYSTICK_XINPUT
     SDL_bool bOpenedXInputDevices[XUSER_MAX_COUNT];
     SDL_zeroa(bOpenedXInputDevices);
 #endif
@@ -363,7 +363,7 @@ static int SDLCALL SDL_JoystickThread(void *_data)
 #else
         {
 #endif
-#if SDL_JOYSTICK_XINPUT
+#ifdef SDL_JOYSTICK_XINPUT
             /* WM_DEVICECHANGE not working, poll for new XINPUT controllers */
             SDL_CondWaitTimeout(s_condJoystickThread, s_mutexJoyStickEnum, 1000);
             if (SDL_XINPUT_Enabled() && XINPUTGETCAPABILITIES) {

src/joystick/windows/SDL_xinputjoystick.c

@@ -22,7 +22,7 @@
 
 #include "../SDL_sysjoystick.h"
 
-#if SDL_JOYSTICK_XINPUT
+#ifdef SDL_JOYSTICK_XINPUT
 
 #include "SDL_windowsjoystick_c.h"
 #include "SDL_xinputjoystick_c.h"