- For some of these I changed `context` to `describe` as it fit better
rather than contriving a "when", "with" or "without", or massively
restructuring the tests.
This makes use of both the existing interfaces and could use the
existing cache file but we'll create a new one and cleanup the old one
to avoid issues and use a more consistent name.
Cache all the non-weak dynamic library links for a keg rather than the
result of running `brew linkage`. This means that we correctly handle
changes to e.g. what non-keg files are present on disk.
