udev: complete rework

- systemd puts all into one output now (except for man),
  because I wasn't able to fix all systemd/udev refernces
  for NixOS to work well
- libudev is now by default *copied* into another path,
  which is what most packages will use as build input :-)
- pkgs.udev = [ libudev.out libudev.dev ]; because there are too many
  references that just put `udev` into build inputs (to rewrite them all),
  also this made "${udev}/foo" fail at *evaluation* time
  so it's easier to catch and change to something more specific

nixos/modules/services/hardware/udev.nix

@@ -58,13 +58,13 @@ let
           --replace \"/bin/mount \"${pkgs.utillinux}/bin/mount
       done
 
-      echo -n "Checking that all programs called by relative paths in udev rules exist in ${pkgs.udev.out}/lib/udev... "
+      echo -n "Checking that all programs called by relative paths in udev rules exist in ${udev}/lib/udev... "
       import_progs=$(grep 'IMPORT{program}="[^/$]' $out/* |
         sed -e 's/.*IMPORT{program}="\([^ "]*\)[ "].*/\1/' | uniq)
       run_progs=$(grep -v '^[[:space:]]*#' $out/* | grep 'RUN+="[^/$]' |
         sed -e 's/.*RUN+="\([^ "]*\)[ "].*/\1/' | uniq)
       for i in $import_progs $run_progs; do
-        if [[ ! -x ${pkgs.udev.out}/lib/udev/$i && ! $i =~ socket:.* ]]; then
+        if [[ ! -x ${udev}/lib/udev/$i && ! $i =~ socket:.* ]]; then
           echo "FAIL"
           echo "$i is called in udev rules but not installed by udev"
           exit 1