ddraw/tests: Fix compilation on systems that don't support nameless unions.

[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=11972

Your paranoid android.


=== w8 (32 bit visual) ===
visual.c:1617: Test failed: unexpected colortable on offscreen surface

=== wvistau64 (32 bit ddraw7) ===
ddraw7.c:2524: Test failed: Expected message 0x46, but didn't receive it.
ddraw7.c:2526: Test failed: Expected screen size 1024x768, got 0x0.
ddraw7.c:2532: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2563: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2571: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2598: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2618: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2635: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2662: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2679: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2716: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2727: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2754: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2774: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2791: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2818: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2835: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.
ddraw7.c:2873: Test failed: Expected {0, 0, 1024, 768}, got {-8, -8, 1032, 746}.