80738ed9dc
It's a quick approximation to unblock unstable channels after #48116. This commit isn't ideal, as I suspect most wayland users won't have xserver.enable, so they will lose the icon cache in case they had gtk in system path (otherwise they didn't get cache anyway). I considered using environment.noXlibs, but the nixos tests installing headless systems do *not* get that option, so we would still be pulling gtk in many cases where it's clearly not desired. We need to design this more carefully.
*** NixOS *** NixOS is a Linux distribution based on the purely functional package management system Nix. More information can be found at http://nixos.org/nixos and in the manual in doc/manual.