Added guide button to controller db, changed to use secret XInput function.

core/input/godotcontrollerdb.txt

@@ -2,7 +2,7 @@
 # Source: https://github.com/godotengine/godot
 
 # Windows
-__XINPUT_DEVICE__,XInput Gamepad,a:b12,b:b13,x:b14,y:b15,start:b4,back:b5,leftstick:b6,rightstick:b7,leftshoulder:b8,rightshoulder:b9,dpup:b0,dpdown:b1,dpleft:b2,dpright:b3,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,platform:Windows,
+__XINPUT_DEVICE__,XInput Gamepad,a:b12,b:b13,x:b14,y:b15,start:b4,guide:b10,back:b5,leftstick:b6,rightstick:b7,leftshoulder:b8,rightshoulder:b9,dpup:b0,dpdown:b1,dpleft:b2,dpright:b3,leftx:a0,lefty:a1,rightx:a2,righty:a3,lefttrigger:a4,righttrigger:a5,platform:Windows,
 
 # Android
 Default Android Gamepad,Default Controller,leftx:a0,lefty:a1,dpdown:h0.4,rightstick:b8,rightshoulder:b10,rightx:a2,start:b6,righty:a3,dpleft:h0.8,lefttrigger:a4,x:b2,dpup:h0.1,back:b4,leftstick:b7,leftshoulder:b9,y:b3,a:b0,dpright:h0.2,righttrigger:a5,b:b1,platform:Android,

platform/windows/joypad_windows.cpp

@@ -516,11 +516,13 @@ void JoypadWindows::joypad_vibration_stop_xinput(int p_device, uint64_t p_timest
 void JoypadWindows::load_xinput() {
 	xinput_get_state = &_xinput_get_state;
 	xinput_set_state = &_xinput_set_state;
+	bool legacy_xinput = false;
 	xinput_dll = LoadLibrary("XInput1_4.dll");
 	if (!xinput_dll) {
 		xinput_dll = LoadLibrary("XInput1_3.dll");
 		if (!xinput_dll) {
 			xinput_dll = LoadLibrary("XInput9_1_0.dll");
+			legacy_xinput = true;
 		}
 	}
 
@@ -529,7 +531,9 @@ void JoypadWindows::load_xinput() {
 		return;
 	}
 
-	XInputGetState_t func = (XInputGetState_t)GetProcAddress((HMODULE)xinput_dll, "XInputGetState");
+	// (LPCSTR)100 is the magic number to get XInputGetStateEx, which also provides the state for the guide button
+	LPCSTR get_state_func_name = legacy_xinput ? "XInputGetState" : (LPCSTR)100;
+	XInputGetState_t func = (XInputGetState_t)GetProcAddress((HMODULE)xinput_dll, get_state_func_name);
 	XInputSetState_t set_func = (XInputSetState_t)GetProcAddress((HMODULE)xinput_dll, "XInputSetState");
 	if (!func || !set_func) {
 		unload_xinput();