Fix incorrect syntax for xref in mix.exs

[fertapric]

The documentation specifies this should be a list of module or {module, function, arity}.

The current configuration causes this error trace:

could not compile dependency :ex_cldr_dates_times, "mix compile" failed. You can recompile this dependency with "mix deps.compile ex_cldr_dates_times", update it with "mix deps.update ex_cldr_dates_times" or clean it with "mix deps.clean ex_cldr_dates_times"
** (Protocol.UndefinedError) protocol Enumerable not implemented for :eprof
    (elixir) lib/enum.ex:1: Enumerable.impl_for!/1
    (elixir) lib/enum.ex:141: Enumerable.reduce/3
    (elixir) lib/enum.ex:3015: Enum.reverse/1
    (elixir) lib/enum.ex:2649: Enum.to_list/1
    (elixir) lib/map_set.ex:78: MapSet.new/1
    (mix) lib/mix/tasks/xref.ex:189: Mix.Tasks.Xref.warnings/1
    (mix) lib/mix/tasks/compile.xref.ex:56: Mix.Tasks.Compile.Xref.run_xref/0
    (mix) lib/mix/tasks/compile.xref.ex:38: Mix.Tasks.Compile.Xref.run/1

on Elixir 1.8.2 (and probably in other versions).

Or maybe the whole :xref configuration should be removed 🙂

[kipcole9]

Thanks for the PR, much appreciated. I added the xref configuration because on Elixir 1.11 I was getting a compiler warning because :eprof wasn't being detected as a dependency and I hate libraries that emit compiler warnings.

I have removed the xref configuration, sent a PR to the exprof library and will log an issue with Elixir since the configuration I added was directly from the compiler error message.

[kipcole9]

Published ex_cldr_dates_times version 2.6.4 just now with the following changelog entry:

Bug Fixes

• Remove xref section from the project in mix.exs. The fixes an error where the configuration for xref was incorrect and causing compiler errors on some versions of Elixir. Closes #19. Thanks to @fertapric.

• Make dependencies eprof and dialyixir optional so that they aren't dragged into host apps unnecessarily.