Log Message:
pkgtools/pkglint: update to 19.4.6

Changes since 19.4.5:

Added the --network option, which allows pkglint to use HTTP calls for
determining whether the homepage of a package is reachable.

Added migration from http URLs to the corresponding https URLs. This is
only done if the https URL is indeed reachable or well-known to support
https.

Added migration from https SourceForge URLs back to http URLs since a
previous pkglint run had migrated URLs to non-working https URLs. See
https://mail-index.netbsd.org/pkgsrc-changes/2020/01/18/msg205146.html.

Added a warning for HOMEPAGE that uses ftp:// since that is not
user-friendly. In the same way, download-only host names on SourceForge
are not suitable as a homepage since they usually only generate a 404.