nixos/modules: pkgconfig -> pkg-config

nixos/modules/installer/tools/nixos-option/default.nix

···
-{lib, stdenv, boost, cmake, pkgconfig, nix, ... }:
+{lib, stdenv, boost, cmake, pkg-config, nix, ... }:
 stdenv.mkDerivation rec {
   name = "nixos-option";
   src = ./.;
-  nativeBuildInputs = [ cmake pkgconfig ];
+  nativeBuildInputs = [ cmake pkg-config ];
   buildInputs = [ boost nix ];
   meta = {
     license = stdenv.lib.licenses.lgpl2Plus;

nixos/modules/services/networking/dnscrypt-wrapper.nix

···
   # correctly implement key rotation of dnscrypt-wrapper ephemeral keys.
   dnscrypt-proxy1 = pkgs.callPackage
     ({ stdenv, fetchFromGitHub, autoreconfHook
-    , pkgconfig, libsodium, ldns, openssl, systemd }:
+    , pkg-config, libsodium, ldns, openssl, systemd }:
 
     stdenv.mkDerivation rec {
       pname = "dnscrypt-proxy";
···
 
       configureFlags = optional stdenv.isLinux "--with-systemd";
 
-      nativeBuildInputs = [ autoreconfHook pkgconfig ];
+      nativeBuildInputs = [ autoreconfHook pkg-config ];
 
       # <ldns/ldns.h> depends on <openssl/ssl.h>
       buildInputs = [ libsodium openssl.dev ldns ] ++ optional stdenv.isLinux systemd;