libkadm5clnt: Fix library symlink install

libkadm5clnt_mit installs a symlink from libkadm5clnt.so for backward
compatibility, but it neglected to include the package tags, so the
symlink was missing from pkgbase builds. Add ${DEV_TAG_ARGS} to the
install command.

Reported by: Mark Millard <marklmi@yahoo.com>
MFC after: 1 day
Reviewed by: emaste
Sponsored by: https://www.patreon.com/bsdivy
Differential Revision: https://reviews.freebsd.org/D53574

(cherry picked from commit 707507c27f69f16de0ce3efee21b20d4f76328f8)