Add "auto-accept" to LICENSE_PERMS.
It is not entirely clear to me what the policy is to decide whether a
license can be auto-accepted, but for now this makes it possible to build
the port without supervision (eg. with BATCH=1).
- Modernize and simplify the archivers/p7zip port's Makefile by getting rid
of some sed calls, supporting staging.
- Set LICENSE for the port. 
- Get rid of the MINIMAL and MODULES options. They were not very useful and
its handling was needlessly complicating the Makefile logic. We now always
build as if MINIMAL was unset.
- Stop installing the p7zip and Client7z wrappers.
- Move the installation of the RAR decompression codec to
archivers/p7zip-codec-rar, as its source code uses a more restrictive
license than the LGPL21 used for the rest of the code base.
PR: ports/185238 
Submitted by: Hardy Schumacher <email@example.com>