[Bug 55688] dmusic:dmusic - test_default_gm_collection() crashes on macOS

[WineHQ Bugzilla]

https://bugs.winehq.org/show_bug.cgi?id=55688

--- Comment #3 from Rémi Bernon  ---
I think we should be able to check in the tests whether the default
"C:\windows\system32\gm.dls" has been found and successfully loaded, although
it should always be there on Windows, it could be at least a todo_wine.

Another option I imagined was to have a dummy builtin, always present,
"gm.dls", which we would detect somehow and still override with system-provided
SF2, but I'm not completely sure how to do that yet.