[PATCH] mfplat/tests: Fix test crash on old Windows 10 systems.

[Marvin]

Hi,

While running your changed tests, 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=104049

Your paranoid android.


=== w1064v1809 (32 bit report) ===

mfplat:
mfplat.c:3221: Test failed: Unexpected refcount 0, expected 1.