Function apply_host_feature_gates 

fn apply_host_feature_gates(cmd: Command, bootconfig_extra: bool) -> Command

Hide subcommands whose backing functionality is missing on the running host from --help. Invoking one is rejected before parsing by host_feature_gate_rejects.

bootconfig_extra is whether the host ostree supports bootconfig-extra, which loader-entries requires; see crate::loader_entries::ostree_supports_bootconfig_extra.