Added ./autogen.sh during build(), otherwise fails with:

checking for libgcrypt-config... no
checking for LIBGCRYPT - version >= 1.0.0... no
configure: error: *** libgcrypt not found!

Now supported upstream, see https://gitlab.com/pdfgrep/pdfgrep/-/merge_requests/17

FTR, commands used to change arch=() and then verify the changes:

$ sed -Ei "/^arch=/{s/ *?['\"]?i686['\"]? *?//;s/ *$//}" */*/PKGBUILD*

$ grep -r i686 * | grep arch= | grep -v repos

$ svn diff | grep -A 1 ^-[^-] | grep -v -- -- | cut -c2- |
  while IFS=$'\n' read -r l1; IFS=$'\n' read -r l2; do
    echo "$l1 -> $l2"
  done | sort -u