linuxPackages.v4l2loopback: fix compilation with linux-4.14

+1
+1
pkgs/os-specific/linux/v4l2loopback/default.nix
··· 17 export PATH=${kmod}/sbin:$PATH 18 ''; 19 20 buildInputs = [ kmod ]; 21 22 makeFlags = [
··· 17 export PATH=${kmod}/sbin:$PATH 18 ''; 19 20 + nativeBuildInputs = kernel.moduleBuildDependencies; 21 buildInputs = [ kmod ]; 22 23 makeFlags = [