Update graphics/feh to 2.5.

Update graphics/feh to 2.5.

pkgsrc changes
--------------

Don't mess with CFLAGS. I can't remember why that was even necessary, and it
breaks the Linux build.

Should fix PR pkg/46390.

upstream changes
----------------

* Add R, * and / bindings for keypad begin, keypad * and keypad /
* Try to convert unloadable files with imagemagick for up to 5 seconds
* Add --magick-timeout option to set imagemagick conversion timeout or disable
it altogether
* Clean up temporary / to-delete files when receiving SIG{INT,TERM,QUIT}
* Do not scroll past image borders when using key bindings
* --loadable / --unloadable: indicate result in exit status