Wrong ISO speed when it is over 65535

[Masahiro Kitagawa]

Describe the bug
ISO speed shown in metadata table is clipped to maximum value 65535.

To Reproduce
Steps to reproduce the behavior:

1. Select an image that was taken with ISO speed higher than 65535.
2. Check the ISO speed value in metadata table.

Expected behavior
The value should be same as camera setting.

Desktop (please complete the following information):

• Version <= 4.2.5 and 5.0.0beta1
• OS: Any

Additional context
EXIF_ISO_SPEED_RATINGS (0x8827) tag value is 16-bit, and 2^16 = 65536.

[Masahiro Kitagawa]

Need to read Anex G in Exif v2.30 spec. cf.

• https://exiftool.org/forum/index.php?topic=4090.0
• https://www.cipa.jp/std/documents/j/DC-008-2012_J.pdf (Japanese)