h264: skip chroma edges at the picture boundary while deblocking 4:4:4

This handles macroblock edges for the chroma components in the same way
as for the luma compoment for 4:4:4 streams. The Spec explicitly states
that the deblocking filter is not applied to edges at the boundary of
the picture.
Signed-off-by: Janne Grunau <janne-libav@jannau.net>

libavcodec/h264.c

@@ -2361,6 +2361,7 @@ static av_always_inline void xchg_mb_border(H264Context *h, uint8_t *src_y,
     }
     if (simple || !CONFIG_GRAY || !(h->flags & CODEC_FLAG_GRAY)) {
         if (chroma444) {
+            if (deblock_top) {
                 if (deblock_topleft) {
                     XCHG(top_border_m1 + (24 << pixel_shift), src_cb - (7 << pixel_shift), 1);
                     XCHG(top_border_m1 + (40 << pixel_shift), src_cr - (7 << pixel_shift), 1);
@@ -2373,6 +2374,7 @@ static av_always_inline void xchg_mb_border(H264Context *h, uint8_t *src_y,
                     XCHG(h->top_borders[top_idx][h->mb_x + 1] + (16 << pixel_shift), src_cb + (17 << pixel_shift), 1);
                     XCHG(h->top_borders[top_idx][h->mb_x + 1] + (32 << pixel_shift), src_cr + (17 << pixel_shift), 1);
                 }
+            }
         } else {
             if (deblock_top) {
                 if (deblock_topleft) {