avcodec/evc_parse: use a local EVCParserSliceHeader when parsing slices

There's no need to store EVC_MAX_PPS_COUNT amount of slice headers in EVCParserContext.

Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/evc_parser.c

@@ -209,10 +209,8 @@ static void evc_parser_close(AVCodecParserContext *s)
 
     for(int i = 0; i < EVC_MAX_PPS_COUNT; i++) {
         EVCParserPPS *pps = ctx->pps[i];
-        EVCParserSliceHeader *sh = ctx->slice_header[i];
 
         av_freep(&pps);
-        av_freep(&sh);
     }
 }