beamPackages: turn on debug_info for beam packages

This allows you to turn on debug infor for all the beam packages in the
system with a single change at the top level. This is required for
debugging and dialyzer work. It also allows you to switch it on on a
package by package basis.

pkgs/development/interpreters/elixir/default.nix

@@ -21,6 +21,8 @@ stdenv.mkDerivation rec {
 
   setupHook = ./setup-hook.sh;
 
+  inherit debugInfo;
+
   buildFlags = if debugInfo
    then "ERL_COMPILER_OPTIONS=debug_info"
    else "";