plasma-workspace: use impure wrappers

Changed files
+1
pkgs
desktops
plasma-5.4
plasma-workspace
+1
pkgs/desktops/plasma-5.4/plasma-workspace/default.nix
···
'';
postInstall = ''
export QT_WRAPPER_IMPURE=1
+
export KDE_WRAPPER_IMPURE=1
wrapKDEProgram "$out/bin/ksmserver"
wrapKDEProgram "$out/bin/plasmawindowed"
wrapKDEProgram "$out/bin/kcminit_startup"