qtile: Fix using qtile together with desktop

Funny bug, which prevent qtile to co-exists with desktop manager
(or program pretending to be DE)

Changed files
+1 -1
nixos
modules
services
x11
window-managers
+1 -1
nixos/modules/services/x11/window-managers/qtile.nix
···
services.xserver.windowManager.session = [{
name = "qtile";
start = ''
-
${pkgs.qtile}/bin/qtile
+
${pkgs.qtile}/bin/qtile &
waitPID=$!
'';
}];