avcodec/utils: Do not merge side data for encoders

With side data now being added to every MPEG*/H26* video encoder
in the form of a quality scalar, software which simply stores
the pkt->data to get an ES stream would break.
This also as a side-effect makes the code faster

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>

libavcodec/utils.c

@@ -2213,8 +2213,6 @@ FF_ENABLE_DEPRECATION_WARNINGS
 
     if (ret < 0 || !*got_packet_ptr)
         av_free_packet(avpkt);
-    else
-        av_packet_merge_side_data(avpkt);
 
     emms_c();
     return ret;