C and C++ compiler extensions disabled in extra-cmake-modules

[Albert Astals Cid]

With https://invent.kde.org/frameworks/extra-cmake-modules/-/merge_requests/145 we have disabled the C and C++ specific compiler extensions.

This has already let to some code failing to build that was using C extensions, and has been fixed by simply requiring a more recent C
  https://invent.kde.org/frameworks/kguiaddons/-/merge_requests/23
  https://invent.kde.org/frameworks/bluez-qt/-/merge_requests/10
  https://invent.kde.org/frameworks/kwayland/-/merge_requests/34

If you find yourself with a build failing when it use to work, this may be the cause.

I'll be happy to help figure out what the fix is.

Sorry for the [potential] trouble.

Cheers,
  Albert