"Mirror" orientations ignored in RawTherapee.

[throwaway-60789]

Short description
When the image's orientation is set to "mirror" ones, it is ignored and opened as the "normal" orientation.
Some "selfie" cameras only flips the JPG output, and the raw photo is not flipped. You can manually set the orientation to 2 using exiftool to change the orientation without changing the image data.

Steps to reproduce

for i in {1..8}; do exiftool -Orientation=$i -n source.dng -o $i.dng; done

Expected behavior

Additional information

• Version of RawTherapee: 5.11 db575c6 (AppImage)
• Version of your operating system: Debian Sid