Revert "all-packages: warn when using deprecated attributes"

This reverts commit c53018c9a1. This
causes problems for "nix-env -qa", so we'll have to come up with a
clean solution first.

Issue #9456.

pkgs/top-level/all-packages.nix

@@ -15282,13 +15282,8 @@ let
 
   mg = callPackage ../applications/editors/mg { };
 
-}
-  ### Aliases to attributes converted to the dashed-style.
-  // lib.mapAttrs (name: builtins.trace
-    ( "Warning: using a deprecated attribute '${name}'."
-    + " CamelCase and under_scores are replaced by dashed-names"
-    + " to match the nix-env names better."))
-{ # warnings since 2015-09
+
+  # Attributes for backward compatibility.
   adobeReader = adobe-reader;
   arduino_core = arduino-core;  # added 2015-02-04
   asciidocFull = asciidoc-full;  # added 2014-06-22
@@ -15297,6 +15292,8 @@ let
   lttngTools = lttng-tools;  # added 2014-07-31
   lttngUst = lttng-ust;  # added 2014-07-31
   jquery_ui = jquery-ui;  # added 2014-09-07
+  youtubeDL = youtube-dl;  # added 2014-10-26
+  youtube-dl = pythonPackages.youtube-dl; # added 2015-06-07
   rdiff_backup = rdiff-backup;  # added 2014-11-23
   htmlTidy = html-tidy;  # added 2014-12-06
   libtidy = html-tidy;  # added 2014-12-21
@@ -15304,17 +15301,8 @@ let
   sqliteInteractive = sqlite-interactive;  # added 2014-12-06
   nfsUtils = nfs-utils;  # added 2014-12-06
   buildbotSlave = buildbot-slave;  # added 2014-12-09
-  rssglx = rss-glx; #added 2015-03-25
-
-}
-  ### Other attribute aliases for backward compatibility.
-  // lib.mapAttrs
-      (name: builtins.trace "Warning: using a deprecated attribute '${name}'.")
-{ # warnings since 2015-09
-  youtubeDL = youtube-dl;  # added 2014-10-26
-  youtube-dl = pythonPackages.youtube-dl; # added 2015-06-07
   cool-old-term = cool-retro-term; # added 2015-01-31
-
+  rssglx = rss-glx; #added 2015-03-25
   haskell-ng = haskell;                 # 2015-04-19
   haskellngPackages = haskellPackages;  # 2015-04-19
   inherit (haskell.compiler) jhc uhc;   # 2015-05-15