package/libexif: security bump to version 0.6.23

- Drop patches (already in version)
- Fix some more denial of service (compute time or stack exhaustion)
  counter-measures added that avoid minutes of decoding time with
  malformed files found by OSS-Fuzz

https://github.com/libexif/libexif/releases/tag/v0.6.23



Signed-off-by: Fabrice Fontaine <fontaine.fabrice@gmail.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>