KWayland backport request, fix include path in generated pkgconfig file

[Ahmad Samir]

Due to an error with the previous change to re-layout the include dir paths in KF, the generated 
pkgconfig file had the wrong include path, this should be fixed with:
https://invent.kde.org/frameworks/kwayland/commit/9e70125d2991a2a2ab64e606ccabd223848945b0

Thanks to Gentoo users/devs for the heads up.

Best regards,
Ahmad Samir