mpegvideo: Drop exchange_uv() function and use its code directly

Code is small enough that there is no advantage in a separate function.

libavcodec/mpegvideo.c

@@ -765,15 +765,6 @@ fail:
     return ret;
 }
 
-static void exchange_uv(MpegEncContext *s)
-{
-    int16_t (*tmp)[64];
-
-    tmp           = s->pblocks[4];
-    s->pblocks[4] = s->pblocks[5];
-    s->pblocks[5] = tmp;
-}
-
 static int init_duplicate_context(MpegEncContext *s)
 {
     int y_size = s->b8_stride * (2 * s->mb_height + 1);
@@ -804,8 +795,13 @@ static int init_duplicate_context(MpegEncContext *s)
     for (i = 0; i < 12; i++) {
         s->pblocks[i] = &s->block[i];
     }
-    if (s->avctx->codec_tag == AV_RL32("VCR2"))
-        exchange_uv(s);
+    if (s->avctx->codec_tag == AV_RL32("VCR2")) {
+        // exchange uv
+        int16_t (*tmp)[64];
+        tmp           = s->pblocks[4];
+        s->pblocks[4] = s->pblocks[5];
+        s->pblocks[5] = tmp;
+    }
 
     if (s->out_format == FMT_H263) {
         /* ac values */
@@ -880,8 +876,13 @@ int ff_update_duplicate_context(MpegEncContext *dst, MpegEncContext *src)
     for (i = 0; i < 12; i++) {
         dst->pblocks[i] = &dst->block[i];
     }
-    if (dst->avctx->codec_tag == AV_RL32("VCR2"))
-        exchange_uv(dst);
+    if (dst->avctx->codec_tag == AV_RL32("VCR2")) {
+        // exchange uv
+        int16_t (*tmp)[64];
+        tmp             = dst->pblocks[4];
+        dst->pblocks[4] = dst->pblocks[5];
+        dst->pblocks[5] = tmp;
+    }
     if (!dst->edge_emu_buffer &&
         (ret = frame_size_alloc(dst, dst->linesize)) < 0) {
         av_log(dst->avctx, AV_LOG_ERROR, "failed to allocate context "