return 1 when error during write frame, state changed

Originally committed as revision 13851 to svn://svn.ffmpeg.org/ffmpeg/trunk

ffserver.c

@@ -2187,6 +2187,7 @@ static int http_prepare_data(HTTPContext *c)
                     if (av_write_frame(ctx, &pkt) < 0) {
                         http_log("Error writing frame to output\n");
                         c->state = HTTPSTATE_SEND_DATA_TRAILER;
+                        return 1;
                     }
 
                     len = url_close_dyn_buf(ctx->pb, &c->pb_buffer);