During sanity check, detect and delete packages which have changed PKGNAMES

This avoids a warning and bug in pkg-repo with duplicate package names
which requires manual intervention. This may not be the best solution,
but it is the lowest risk change to get into 3.0.x while there is an
ongoing effort to change PKGNAMES in ports to not conflict with others.
This was a comment for future work
pkgclean: Detect duplicated/renamed packages
Add a function be able to specific something is not supported on a given OS
Make not_for_os really working
Do not build cpdup and make_index on dfly

Obtained from: 	dragonfly branch
Erg fix typo
Quit early if no ports tree are defined

Obtained from:	dragonfly branch
Ignore history for git and support verbose mode

Obtained from:	dragonfly branch
Fix grammar
Return early if no jails are defined

Obtained from:	dragonfly branch
Fix typo

Reported by:	marino
Only markfs prepkg for bulk/testport, not pkgclean
pkgclean: Fix keeping proper pkg when duplicates exist
Fix crash when ALLOW_MAKE_JOBS is set

Reported by:	gjb
Exclude /portdistfiles when running mtree
When detecting stage orphans, don't exclude anything.

This fixes finding /var/run/PORTNAME as an orphan.
Remove 2 variables not used and which are wrong
Make the 'Invalid port origin' error a little more clear
Rever logic so that is does not get catched up by set -e