Plasma-5.8 and KF-5.31 fix

[Andreas Sturmlechner]

Hi,

khotkeys-5.8.5 fails to build with KF-5.31, a fix is available in 5.9 branch 
(commit 617de4bd3fd080d43cce9bdc8af82963960d5c3a) but not in 5.8.

For reference: https://bugs.gentoo.org/show_bug.cgi?id=610040

It would be good to have that backported for 5.8.6 release.

Regards,
Andreas