- Find menus by ID: Proper fallback to popup menus.
- Use the menu ID, not the handle for the fallback.
- Save the fallback menu's position.

Based on a patch by Rob Shearman.

Also print a warning if HAL support is not compiled in.

buffer for interfaces and the buffer actually used.

Initialise BSTR pointer to NULL before calling BSTR_UserUnmarshal,
otherwise BSTR_UserUnmarshal will try to use the memory in the
pointer.