Fix a possible binary leak in Integer.parse/1

Integer.parse/1 followed this pattern:

    defp do_parse(<<char, rest :: binary>>, ...) do
      ...
      # instead of re-using the original binary, we do this
      {..., <<char, rest :: binary>>}
    end

This causes a new binary to be created instead of `rest` just being a
sub-binary.

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

Author: whatyouhide

lib/elixir/lib/integer.ex

@@ -167,11 +167,11 @@ defmodule Integer do
 
   defp do_parse(_, _), do: :error
 
-  defp do_parse(<<char, rest::binary>>, base, acc) do
+  defp do_parse(<<char, rest::binary>> = bin, base, acc) do
     if valid_digit_in_base?(char, base) do
       do_parse(rest, base, base * acc + parse_digit(char, base))
     else
-      {acc, <<char, rest::binary>>}
+      {acc, bin}
     end
   end