[d3d9] Avoid setting cursor position if we are already at that position

Avoids an infinite loop where we trigger the cursor move window message which calls SetCursorPos and so on and so forth...

Closes #1400

src/d3d9/d3d9_cursor.cpp

@@ -1,10 +1,15 @@
 #include "d3d9_cursor.h"
+#include "d3d9_util.h"
 
 #include <utility>
 
 namespace dxvk {
 
   void D3D9Cursor::UpdateCursor(int X, int Y) {
+    POINT currentPos = { };
+    if (::GetCursorPos(&currentPos) && currentPos == POINT{ X, Y })
+        return;
+
     ::SetCursorPos(X, Y);
   }