Switch to extended Nixpkg's lib

This change makes use of the `extend` function inside `lib` to inject
a new `hm` field containing the Home Manager library functions. This
simplifies use of the Home Manager library in the modules and reduces
the risk of accidental infinite recursion.

PR #994

modules/programs/info.nix

@@ -26,8 +26,6 @@ let
 
   cfg = config.programs.info;
 
-  dag = config.lib.dag;
-
   # Indexes info files found in this location
   homeInfoPath = "${config.home.profileDirectory}/share/info";
 
@@ -57,7 +55,7 @@ in
     home.sessionVariables.INFOPATH =
       "${cfg.homeInfoDirLocation}\${INFOPATH:+:}\${INFOPATH}";
 
-    home.activation.createHomeInfoDir = dag.entryAfter ["installPackages"] ''
+    home.activation.createHomeInfoDir = hm.dag.entryAfter ["installPackages"] ''
       oPATH=$PATH
       export PATH="${lib.makeBinPath [ pkgs.gzip ]}''${PATH:+:}$PATH"
       $DRY_RUN_CMD mkdir -p "${cfg.homeInfoDirLocation}"

modules/programs/mbsync.nix

@@ -4,8 +4,6 @@ with lib;
 
 let
 
-  dag = config.lib.dag;
-
   cfg = config.programs.mbsync;
 
   # Accounts for which mbsync is enabled.
@@ -180,7 +178,7 @@ in
 
     home.activation = mkIf (mbsyncAccounts != []) {
       createMaildir =
-        dag.entryBetween [ "linkGeneration" ] [ "writeBoundary" ] ''
+        hm.dag.entryBetween [ "linkGeneration" ] [ "writeBoundary" ] ''
           $DRY_RUN_CMD mkdir -m700 -p $VERBOSE_ARG ${
             concatMapStringsSep " " (a: a.maildir.absPath) mbsyncAccounts
           }