Revision 497464

textproc/miller: Update to 5.4.0

- Remove DISTVERSIONPREFIX as upstream is no longer using it.
- Improve COMMENT.
- Add a test target.
- 5.4.0 changelog:
  https://github.com/johnkerl/miller/releases/tag/5.4.0

PR:		236547
Reviewed by:	mat
Approved by:	maintainer (timeout, >14 days)
Differential Revision:	https://reviews.freebsd.org/D19593