Fix software UpdateNVTexture non fullscreen (bug #5430)

src/render/SDL_yuv_sw.c

@@ -322,7 +322,7 @@ int SDL_SW_UpdateNVTexturePlanar(SDL_SW_YUVTexture * swdata, const SDL_Rect * re
     /* Copy the UV or VU plane */
     src = UVplane;
     dst = swdata->pixels + swdata->h * swdata->w;
-    dst += rect->y/2 * ((swdata->w + 1)/2) + rect->x/2;
+    dst += rect->y * ((swdata->w + 1)/2) + rect->x;
     length = (rect->w + 1) / 2;
     length *= 2;
     for (row = 0; row < (rect->h + 1)/2; ++row) {