D8756: Forbid more syscalls which could modify the filesystem

[David Kahles]

davidk added a reviewer: graesslin.

REPOSITORY
  R133 KScreenLocker

REVISION DETAIL
  https://phabricator.kde.org/D8756

To: davidk, graesslin
Cc: plasma-devel, ZrenBot, progwolff, lesliezhai, ali-mohamed, jensreuterberg, 
abetts, sebas, apol, mart