Log Message:
pkgtools/pkglint: update to 20.4.1

Changes since 20.4.0:

When a package has MAINTAINER set and there are modified local files,
only remind the user once per package that changes should likely be
approved by the maintainer.  Previously there was a reminder once per
file, which was just too much for a package that has Makefile and PLIST
and maybe some patches changed.

Small performance improvement for loading the doc/CHANGES files, since
that costs a few tenths of seconds at every startup.