systemdMinimal: build without glib

This takes glib (and by this, gtk-doc) out of systemdMinimal's build
closure.

pkgs/os-specific/linux/systemd/default.nix

@@ -143,6 +143,7 @@ in stdenv.mkDerivation {
     "-Dsetfont-path=${kbd}/bin/setfont"
     "-Dtty-gid=3" # tty in NixOS has gid 3
     "-Ddebug-shell=${bashInteractive}/bin/bash"
+    "-Dglib=${stdenv.lib.boolToString (glib != null)}"
     # while we do not run tests we should also not build them. Removes about 600 targets
     "-Dtests=false"
     "-Dimportd=${stdenv.lib.boolToString withImportd}"

pkgs/top-level/all-packages.nix

@@ -18660,6 +18660,7 @@ in
     withImportd = false;
     withCryptsetup = false;
     cryptsetup = null;
+    glib = null;
     lvm2 = null;
   };