hevc: always clip luma_log2_weight_denom

Its value shall be between 0 and 7 according to the specifications.

CC: libav-stable@libav.org
Bug-Id: CID 1257502

libavcodec/hevc.c

@@ -251,7 +251,7 @@ static void pred_weight_table(HEVCContext *s, GetBitContext *gb)
     uint8_t luma_weight_l1_flag[16];
     uint8_t chroma_weight_l1_flag[16];
 
-    s->sh.luma_log2_weight_denom = get_ue_golomb_long(gb);
+    s->sh.luma_log2_weight_denom = av_clip_c(get_ue_golomb_long(gb), 0, 7);
     if (s->sps->chroma_format_idc != 0) {
         int delta = get_se_golomb(gb);
         s->sh.chroma_log2_weight_denom = av_clip_c(s->sh.luma_log2_weight_denom + delta, 0, 7);