D24568: Provide clang-format target with a common KDE style file

[Friedrich W. H. Kossebau]

kossebau added subscribers: nalvarez, ochurlaud.

REPOSITORY
  R240 Extra CMake Modules

REVISION DETAIL
  https://phabricator.kde.org/D24568

To: cullmann, #frameworks
Cc: ochurlaud, nalvarez, kossebau, aacid, davidedmundson, dhaumann, apol, 
ognarb, kde-frameworks-devel, kde-buildsystem, LeGast00n, GB_2, bencreasy, 
michaelh, ngraham, bruns