Fix build errors with IH_DirectInput using the Win SDK

* dxguid.lib no longer exists.
* older SDKs (like the v140_xp toolset) don't provide XUSER_MAX_COUNT.

src/arch/InputHandler/InputHandler_DirectInput.cpp

@@ -20,6 +20,12 @@
 #include <WbemIdl.h>
 #include <OleAuto.h>
 
+// this may not be defined if we are using an older Windows SDK. (for instance, toolsetversion v140_xp does not define it)
+// the number was taken from the documentation
+#ifndef XUSER_MAX_COUNT
+#define XUSER_MAX_COUNT 4
+#endif
+
 REGISTER_INPUT_HANDLER_CLASS2( DirectInput, DInput );
 
 static vector<DIDevice> Devices;

src/arch/InputHandler/InputHandler_DirectInputHelper.cpp

@@ -8,9 +8,6 @@
 
 #if defined(_MSC_VER)
 #pragma comment(lib, "dinput8.lib")
-#if defined(_WINDOWS)
-#pragma comment(lib, "dxguid.lib")
-#endif
 #endif
 LPDIRECTINPUT8 g_dinput = nullptr;