Remove realloc calls with size 0.

Apparently this is now undefined behavior in C23, so we can no
 no longer rely on it.
Thanks to Mark Harris for the information.

Fixes #2338

Thanks to Harrison Green for the report.

Author: Timothy B. Terriberry

src/info.c

@@ -338,10 +338,16 @@ int opus_tags_set_binary_suffix(OpusTags *_tags,
   ncomments=_tags->comments;
   ret=op_tags_ensure_capacity(_tags,ncomments);
   if(OP_UNLIKELY(ret<0))return ret;
-  binary_suffix_data=
-   (unsigned char *)_ogg_realloc(_tags->user_comments[ncomments],_len);
-  if(OP_UNLIKELY(binary_suffix_data==NULL))return OP_EFAULT;
-  memcpy(binary_suffix_data,_data,_len);
+  if(_len!=0){
+    binary_suffix_data=
+     (unsigned char *)_ogg_realloc(_tags->user_comments[ncomments],_len);
+    if(OP_UNLIKELY(binary_suffix_data==NULL))return OP_EFAULT;
+    memcpy(binary_suffix_data,_data,_len);
+  }
+  else{
+    _ogg_free(_tags->user_comments[ncomments]);
+    binary_suffix_data=NULL;
+  }
   _tags->user_comments[ncomments]=(char *)binary_suffix_data;
   _tags->comment_lengths[ncomments]=_len;
   return 0;
@@ -721,8 +727,14 @@ static int opus_picture_tag_parse_impl(OpusPictureTag *_pic,const char *_tag,
      for URLs.*/
   _buf_sz-=i;
   memmove(_buf,_buf+i,sizeof(*_buf)*_buf_sz);
-  _buf=(unsigned char *)_ogg_realloc(_buf,_buf_sz);
-  if(_buf_sz>0&&_buf==NULL)return OP_EFAULT;
+  if(_buf_sz>0){
+    _buf=(unsigned char *)_ogg_realloc(_buf,_buf_sz);
+    if(_buf==NULL)return OP_EFAULT;
+  }
+  else{
+    _ogg_free(_buf);
+    _buf=NULL;
+  }
   _pic->type=picture_type;
   _pic->width=width;
   _pic->height=height;