PSA: libkscreen dependency bumped to Qt 5.4

[Sebastian Kügler]

Quick announcement: We bumped the required Qt version of libkscreen today to 
Qt 5.4 (it was 5.2). The reason is a regression in Qt which caused a crash on 
teardown of the QScreen backend. We fixed it by using API which was new in Qt 
5.4.

I don't expect this to be a problem, as the dependency for Plasma has already 
been bumped to 5.6 recently, but I thought a heads-up wouldn't hurt, still.

Cheers,
-- 
sebas

Sebastian Kügler    •    http://vizZzion.org    •    http://www.kde.org