
Current Xwayland has marked the command line option "-listen" as deprecated in favor of "-listenfd". Use the pkg-config variable "have_listenfd" (if available) from Xwayland to determine if we should use that option, to avoid a deprecation warning when spawning Xwayland. Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1682>