feh: update to 3.9

* Release v3.9
    * Fix compilation on macOS by defining _DARWIN_C_SOURCE for
      mkdtemp and mkstemps. (Patch by Ryan Schmidt)
    * Remove magic byte check before passing an image to Imlib2.
      This check was introduced in feh 3.6 to work around an issue with
      Imlib2 being slow to determine image loadability in some cases
      <https://phab.enlightenment.org/T8739>. By now, an Imlib2 version without
      this issue should be available in all recent distributions, so the check
      in feh is no longer required. For a slight speed-up, or to use feh with
      an affected Imlib2 version (1.6.x or 1.7.0), compile feh with 'magic=1'.
      In this case, feh will use libmagic to determine whether a file is an
      image, and only pass images to Imlib2.
    * Fix crash (segmentation fault due to null pointer dereference) when
      toggling fullscreen mode while moving the cursor.
    * Note that feh no longer supplies its own getopt_long function.
      getopt_long is provided by a wide range of libc implementations, so
      there is no need for feh to duplicate it. (Patch by Guilherme Janczak)


(nia)