install.pl:
Consider putting perl modules in appropriate place for Homebrew if in use.

Instead of doing pre-check audit, check the specific files in the tar.

(Fixed 1.3b) Need chown pledge in addition to fattr to cover the chown
in Archive::Tar setting gid on files when root is not a member of gid.

(Done 1.3a) Make second signature verification also fail fast.

(DONE 1.3) Modified locking and unlocking behavior to unlock only if necessary
and to only re-lock if we did the unlock. Remove bareword filehandles (also
in pkg_info.pl).

(DONE) perl modules need to go to a different location for Linux,
probably best to go with /usr/local/lib/site_perl (do substitution
when path is /usr/local/libdata/perl5/site_perl)
Ditto for macOS, everything in macOS @INC has the perl version # in
it, best may be /Library/Perl/Updates/<version>/
(Alternatively, could leave things in place and create a hard link
in the new place.) Better is probably to extract to new place, creating
extra dir if needed, and change +CONTENTS, so that no equivalent change
need be made to minimal_pkg_delete. (DONE)

install: register the package in /var/db/pkg (DONE)
   This means it won't install again over an existing installation of the
   same version.
To also do:
* Use @sample, copy sample config files only if there isn't already one there.
  (DONE)
* If an older version of the package is installed, uninstall it but leave
  configs untouched unless it is unchanged from the original sample.
  (In +CONTENTS, file name is followed by @sha and @size and @ts (timestamp)
  that can be set by the perl utime function but should already come from
  the tar file content; @sample follows
  the example config file with path to install it, could get even more
  ambitious and look for conf basename starting with 'macOS' or 'linux' and
  installing the appropriate config based on OS instead of the default
  OpenBSD one.)
  Note: @sample could include an /etc subdir in one line and the conf file
  in the subsequent line (reportnew, rsync-tools). The second line has the
  config file name as the basename, would be good to prepend 'macos' if such
  a file exists and os=darwin, or 'linux' if a file exists and os=linux (DONE)
* pkg_info displays pkg name and first line of +DESC for all installed
  packages (DONE)
* Maybe right way to do this is create a separate pkg_add, pkg_delete,
  and pkg_info?  Or is that excessive?  It is nice to have the minimal
  capability built-in. Only really need minimal pkg_delete for updating.
(Above DONE)
* If really ambitious, add +REQUIRES and +REQUIRED_BY and manage package
  dependencies. (based on @depend, @wantlib ... catch is that on linux
  or macOS, stuff may be installed by other means, e.g., want to check
  apt installs on linux--Debian: /var/lib/dpkg/info/package-name.list (w/o
  version # in name--no version info recorded?) also package-name.md5sums
  list includes line for each dir starting at /.; md5sums includes all the
  file md5s.

Provide a way to run install without being in single-user mode if the
required unlocking is only uchg. (Maybe just a -f force option that
also passes it along to syslock/sysunlock.) (DONE)

Can install run as non-root?  The two parts that need to run as root are
the tar expansion and the pkg_add.  Well, actually all -- because it has
to run in single-user mode for immutable file systems.
