Example file:
[line.dwg.gz](https://github.com/LibreDWG/libredwg/files/12373403/line.dwg.gz)

Decoding output:
```
=======> Thumbnail:       3165
```

Detection of thumbnail:
```
  00000c5d 3080 DWG_SENTINEL_THUMBNAIL_BEGIN [..16]
  000050f8 3081 DWG_SENTINEL_THUMBNAIL_END [..16]
```

Begin address is right, but searching for a second sentinel doesn't work.
Don't decode AC1014 thumbnail
This is a GitHub Issue
repo:libredwg
owner:LibreDWG
Title : Don't decode AC1014 thumbnail
Issue date:

--- start body ---
Example file:
[line.dwg.gz](https://github.com/LibreDWG/libredwg/files/12373403/line.dwg.gz)

Decoding output:
```
=======> Thumbnail:       3165
```

Detection of thumbnail:
```
  00000c5d 3080 DWG_SENTINEL_THUMBNAIL_BEGIN [..16]
  000050f8 3081 DWG_SENTINEL_THUMBNAIL_END [..16]
```

Begin address is right, but searching for a second sentinel doesn't work.
--- end body ---
