[PATCH v2 0/4] MR8500: Some improvements to widl.

[eric pouech (＠epo)]

This MR improves widl with  :
- fixes a segfault when inheriting from an incomplete interface
  (prints an error message instead),
- supports (for C++) inheriting from interfaces which are declared
  after the declaration of the derived interface.

--
  v2: include: Remove duplicated declarations in .idl files.
      tools/widl: Ensure inherited interface is declared before using it.
      tools/widl: Remove unneeded condition.
      tools/widl: Fix segfault when inheriting from an incomplete interface.

https://gitlab.winehq.org/wine/wine/-/merge_requests/8500