ModuleInitFlags is missing MODULE_INIT_COMPRESSED_FILE

[sinkingpoint]

For loading compressed modules, we have to pass MODULE_INIT_COMPRESSED_FILE into the init_module functions, but this variant doesn't exist on the ModuleInitFlags enum (https://github.com/nix-rust/nix/blob/master/src/kmod.rs#L59-L64)

[SteveLauC]

Looks like it is easy to add, PR welcome:)