D23692: kdesu: set kernel flags to prevent ptrace instead of relying on setgid

[Fabian Vogt]

fvogt added a reviewer: Frameworks.

REPOSITORY
  R299 KDESu

REVISION DETAIL
  https://phabricator.kde.org/D23692

To: maltek, adridg, #frameworks
Cc: kde-frameworks-devel, LeGast00n, GB_2, michaelh, ngraham, bruns