Some ports may have more than one `config.sub` that is in use (vendored
dependencies, etc.). Instead of fiddling about with space-delimited
strings, let's just make that setting into an array right away.
The new `use_fresh_config_sub` option puts the config.sub in the root of
the tree, but `readline` puts it in the `support/` folder. So we need to
tell the ports infrastructure to place the file in that folder.
All of these patches did the same thing, which is already in upstream
config.sub.
With this change, we need only add `use_fresh_config_sub=true` to
the package.sh file.
Note that this is not done automatically in case the port has a modified
config.sub file.
