Just ensure the pointer and return value are correct from GetGraph.  I plan
to extend these tests at a later date.  The tests also show that IDirectMusicPerformance8
has a internal IDirectMusicGraph implementation, returned via QueryInterface.
Signed-off-by: Alistair Leslie-Hughes <leslie_alistair@hotmail.com>
Signed-off-by: Michael Stefaniuc <mstefani@winehq.org>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>