ConfigureChecks.cmake calls check_function_exists() and check_include_files()
without including the modules that define them:
ConfigureChecks.cmake:14: Unknown CMake command "check_function_exists"
Upstream gets away with it because a native KDE configure has already pulled
those modules in transitively by that point; that does not happen here. CMake
documents both as requiring an explicit include(), so adding them is what
upstream should have done rather than a workaround.
vasilito
efa29a3207