Rely on loaded_applications instead of running ones

If the application is loaded, it is enough for its
modules to be available for autocompletion. This also
simplifies the code and makes completion faster.

Signed-off-by: José Valim <jose.valim@plataformatec.com.br>

Author: José Valim

lib/iex/lib/iex/autocomplete.ex

@@ -177,21 +177,13 @@ defmodule IEx.Autocomplete do
   end
 
   defp get_modules_from_applications do
-    for {app, _, _} <- which_applications(),
+    for {app, _, _} <- :application.loaded_applications(),
         {_, modules} = :application.get_key(app, :modules),
         module <- modules do
       Atom.to_string(module)
     end
   end
 
-  defp which_applications() do
-    try do
-      :application.which_applications(5000)
-    catch
-      :exit, {:timeout, _} -> [:elixir, :iex]
-    end
-  end
-
   defp match_module_funs(mod, hint) do
     case ensure_loaded(mod) do
       {:module, _} ->