[PATCH 5/9] d3d11: Implement {d3d10, d3d11}_geometry_shader_GetDevice().

[Henri Verbeet]

For what it's worth, the original reason geometry shaders and input
layouts don't have a GetDevice() implementation was that it was a bit
harder to add test coverage for them than for the rest of the
interfaces. It's probably easy enough now, so please add some geometry
shader coverage to test_create_shader(). You can probably use the
shader from test_clear_state().