[3/3] user32/tests: Add test for GetWindowDisplayAffinity.

[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=31812

Your paranoid android.


=== w7u (32 bit win) ===
win.c:9858: Test failed: SetWindowDisplayAffinity returned with 8
win.c:9862: Test failed: GetWindowDisplayAffinity returned unexpected affinity 0
win.c:9865: Test failed: SetWindowDisplayAffinity returned with 8

=== w7pro64 (32 bit win) ===
win.c:9858: Test failed: SetWindowDisplayAffinity returned with 8
win.c:9862: Test failed: GetWindowDisplayAffinity returned unexpected affinity 0
win.c:9865: Test failed: SetWindowDisplayAffinity returned with 8

=== w7pro64 (64 bit win) ===
win.c:9858: Test failed: SetWindowDisplayAffinity returned with 8
win.c:9862: Test failed: GetWindowDisplayAffinity returned unexpected affinity 0
win.c:9865: Test failed: SetWindowDisplayAffinity returned with 8