feature request for patch-only option

[gspeicher]

This issue is a feature request for a new "patch-only" option, similar to -F (fetch-only) or (--force-configure) but will fetch, configure, extract, and patch the selected ports and their dependencies. This will allow an administrator to perform this operation ahead of time, in preparation for "portmaster -aCK" later, which will run faster by eliminating the unnecessary disk operations incurred by the extract and patch ports targets during critical downtime while building potentially hundreds of ports during a system upgrade.