Add skipped integration tests for unintrospectable signals
user
```ruby
require 'gir_ffi_test_helper'

GirFFI.setup :Gst
Gst.init []

# Tests behavior of objects in the generated Gio namespace.
describe 'the generated Gst module' do
  describe 'Gst::FakeSink' do
    let(:instance) { Gst::ElementFactory.make('fakesink', 'sink') }

    it 'allows the handoff signal to be connected and emitted' do
      skip
      a = nil
      instance.signal_connect('handoff') { a = 10 }
      instance.signal_emit('handoff')
      a.must_equal 10
    end
  end
end
```
assistant