Simpler code using newer version of wffi.

As of commit 6043e44c91895a6d88fa493ea7c8c1ce9e1c1613 wffi no longer
requires contortions at both phases 0 and 1 with
`current-markdown-files-path` (in fact that parameter is now a
deprecated no-op).

https://github.com/greghendershott/wffi/commit/6043e44c91895a6d88fa493ea7c8c1ce9e1c1613