dmscript/tests: Use a void* instead of void** outer IUnknown argument

[Marvin]

Hi,

While running your changed tests on Windows, I think I found new failures.
Being a bot and all I'm not very good at pattern recognition, so I might be
wrong, but could you please double-check?
Full results can be found at
https://testbot.winehq.org/JobDetails.pl?Key=30436

Your paranoid android.


=== wxppro (32 bit dmscript) ===
dmscript.c:146: Test failed: DirectMusicScriptTrack create failed: 80004003, expected CLASS_E_NOAGGREGATION

=== wvistau64 (32 bit dmscript) ===
01f4:dmscript: unhandled exception c0000005 at 73E47D60

=== w7u (32 bit dmscript) ===
0ac8:dmscript: unhandled exception c0000005 at 72157EA8

=== w7pro64 (32 bit dmscript) ===
0978:dmscript: unhandled exception c0000005 at 73907EA8

=== w8 (32 bit dmscript) ===
0938:dmscript: unhandled exception c0000005 at 69E4804C

=== w864 (32 bit dmscript) ===
0f8c:dmscript: unhandled exception c0000005 at 7451804C

=== w1064 (32 bit dmscript) ===
02bc:dmscript: unhandled exception c0000005 at 7078945E