[PATCH] dxgi/tests: Fix the grammar in a comment.

[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=82452

Your paranoid android.


=== w2008s64 (64 bit report) ===

dxgi:
dxgi.c:5689: Test failed: Got unexpected message 0x1a, hwnd 00000000000600F6, wparam 0x18, lparam 0x22fa18.