minitest_tu_shim compatibility

When running ruby 1.8 and using the minitest_tu_shim (sudo use_minitest yes), and you run the following:

require 'test/unit'
require 'rubygems'
require 'mocha'

class TestA < Test::Unit::TestCase
  def test_a
    obj = Object.new
    obj.expects(:a)
    obj.a
  end
end

you will get errors. For example: NameError: uninitialized constant Test::Unit::TestCase::STARTED

This happens because mocha somehow can't detect that Test::Unit::TestCase is someone else now.

The patch fixed this.

Matthias