sws: dont use the optimized 410->420 unscaled conversion when height%4

Fixes Ticket3594
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libswscale/swscale_unscaled.c

@@ -1585,7 +1585,7 @@ void ff_get_unscaled_swscale(SwsContext *c)
         c->swscale = ff_yuv2rgb_get_func_ptr(c);
     }
 
-    if (srcFormat == AV_PIX_FMT_YUV410P &&
+    if (srcFormat == AV_PIX_FMT_YUV410P && !(dstH & 3) &&
         (dstFormat == AV_PIX_FMT_YUV420P || dstFormat == AV_PIX_FMT_YUVA420P) &&
         !(flags & SWS_BITEXACT)) {
         c->swscale = yvu9ToYv12Wrapper;