I don't think this is possible. There's no way to specify a loader flag in the PE headers - specifically the Import Directory Table. Marking it as a wine builtin dll with `-Wl,--wine-builtin` would introduce winegcc to the wine-mono compilation process, which is likely what we don't want.
Also, this concern is likely invalid since the `system` flag is recursively set during early binding. I haven't checked whether libmono loads those libraries with LoadLibrary or Ldr* APIs, will do a quick grep. In that case, those calls also need to be updated.