user32/tests: Use wine_dbgstr_rect() in the win tests.

[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=23566

Your paranoid android.


=== w2008s64 (32 bit win) ===
win.c:8861: Test failed: GetActiveWindow() = 00000000
win.c:8861: Test failed: GetFocus() = 00000000
win.c:8863: Test failed: Expected foreground window 00080124, got 000200E4
win.c:8866: Test failed: Received WM_ACTIVATEAPP(0), did not expect it.
win.c:8873: Test failed: Expected foreground window 00080124, got 00000000
win.c:8875: Test failed: GetActiveWindow() = 00000000
win.c:8875: Test failed: GetFocus() = 00000000
win.c:8883: Test failed: Received WM_ACTIVATEAPP(1), did not expect it.