Planning to remove pkgtools/pkglint4

[Roland Illig <roland.illig%gmx.de@localhost>]

In 2015 I completely rewrote pkglint and left the old implementation for
those whose preferred platform is not supported by the Go programming
language.

This old pkglint has not been kept up-to-date, it issues many wrong
warnings and doesn't have several new useful warnings. Therefore I'd
like to remove it, in order to avoid confusion.

Who is still using pkglint4, and on which platforms? Please speak up.

Best,
Roland