I#158 - Workaround build error with gtk-doc-1.32

Instead of applying patches to gtk-doc, I've done the workaround in e-d-s instead for now; in either case the struct tm API doesn't end up in the API docs to my knowledge. So for your consideration to make things easier for distros that don't patch gtk-doc-1.32 or devs that have their own gtk-doc. If included, we should have some way to know when we can remove the compat though and get the API actually show up in API docs (NOT considering the workaround as found in gtk-doc, as the API still doesn't get documented with that - I mean once gtk-doc is taught to understand the struct tm somehow).