The GHC package path captured when rwc was built, parallel to the other build-time constants rwc bakes in (libdir and the Paths_rewire data directory): the output of `stack path --ghc-package-path`, run at compile time from the package directory. Nothing if that failed (e.g., a build not driven by stack).

Consumers must validate that the databases still exist before use: the checkout, the stack root, or the snapshot may have moved or been garbage-collected since the build.