build: replace WIN32 => _WIN32

modules/highgui/src/window_QT.cpp

@@ -351,7 +351,7 @@ CV_IMPL int cvWaitKey(int delay)
 
                 //to decrease CPU usage
                 //sleep 1 millisecond
-#if defined WIN32 || defined _WIN32 || defined WIN64 || defined _WIN64
+#if defined _WIN32
                 Sleep(1);
 #else
                 usleep(1000);