James Zern 319860e919 pngdec.c: support ImageMagick app1 exif text data
Test file created with ImageMagick 6.9.13-12:

```
convert test_exif.png test_app1_exif.png
```

Bug: webp:398066379
Change-Id: I10a20de5699fabb0906045994d7d1f4b9e951973
2025-03-05 13:54:07 -08:00
..
2023-09-14 22:43:45 +02:00
2021-11-23 10:13:40 -08:00
2024-07-11 15:59:57 +02:00
2022-03-31 21:43:29 -07:00
2017-03-05 09:38:51 +00:00