gtk: don't hardcode glibc use

(cherry picked from commit 6e6f839093ad080c3a61810e9720165faf103e81)

nixos/modules/services/x11/display-managers/lightdm-greeters/gtk.nix

@@ -22,7 +22,7 @@ let
       # This wrapper ensures that we actually get themes
       makeWrapper ${pkgs.lightdm_gtk_greeter}/sbin/lightdm-gtk-greeter \
         $out/greeter \
-        --prefix PATH : "${pkgs.glibc.bin}/bin" \
+        --prefix PATH : "${lib.getBin pkgs.stdenv.cc.libc}/bin" \
         --set GDK_PIXBUF_MODULE_FILE "${pkgs.librsvg.out}/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache" \
         --set GTK_PATH "${theme}:${pkgs.gtk3.out}" \
         --set GTK_EXE_PREFIX "${theme}" \