Get rid of buggy System.halt/2

Closes #1515, thanks to @AtKaaZ for debugging and pinpointing
this function as the root cause for output issues on Windows.

Author: José Valim

CHANGELOG.md

@@ -40,6 +40,7 @@
   * [Mix] `:test_coverage` option now expect keywords arguments and the `--cover` flag is now treated as a boolean
 
 * backwards incompatible changes
+  * [System] `System.halt/2` was removed since the current Erlang implementation of such function is bugged
 
 # v0.10.0 (2013-07-15)
 

lib/elixir/lib/system.ex

@@ -324,30 +324,25 @@ defmodule System do
   Note that on many platforms, only the status codes 0-255 are supported
   by the operating system.
 
-  For integer status, Erlang runtime system closes all ports and allows async
-  threads to finish their operations before exiting. To exit without such
-  flushing, pass options `[flush: false]` instead.
-
-  For more information, check: http://www.erlang.org/doc/man/erlang.html#halt-2
+  For more information, check: http://www.erlang.org/doc/man/erlang.html#halt-1
 
   ## Examples
 
       System.halt(0)
-      System.halt(1, flush: false)
+      System.halt(1)
       System.halt(:abort)
 
   """
   @spec halt() :: no_return
   @spec halt(non_neg_integer | binary | :abort) :: no_return
-  @spec halt(non_neg_integer | binary | :abort, [] | [flush: false]) :: no_return
-  def halt(status // 0, options // [])
+  def halt(status // 0)
 
-  def halt(status, options) when is_integer(status) or status == :abort do
-    :erlang.halt(status, options)
+  def halt(status) when is_integer(status) or status == :abort do
+    :erlang.halt(status)
   end
 
-  def halt(status, options) when is_binary(status) do
-    :erlang.halt(binary_to_list(status), options)
+  def halt(status) when is_binary(status) do
+    :erlang.halt(binary_to_list(status))
   end
 
   ## Helpers