[2/3] user32/tests: Add tests for button WM_CTLCOLOR* messages.

[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=22345

Your paranoid android.


=== w864 (32 bit msg) ===
msg.c:6482: Test failed: Update region shouldn't be empty
msg.c:6716: Test failed: InvalidateErase: 0: the msg sequence is not complete: expected 0085 - actual 0000
msg.c:6718: Test failed: Paint: 0: the msg sequence is not complete: expected 000f - actual 0000
msg.c:6488: Test failed: Regions are different
msg.c:6488: Test failed: Regions are different
msg.c:6488: Test failed: Regions are different

=== w1064 (32 bit msg) ===
msg.c:6482: Test failed: Update region shouldn't be empty
msg.c:6716: Test failed: InvalidateErase: 0: the msg sequence is not complete: expected 0085 - actual 0000
msg.c:6718: Test failed: Paint: 0: the msg sequence is not complete: expected 000f - actual 0000
msg.c:6488: Test failed: Regions are different
msg.c:6488: Test failed: Regions are different
msg.c:6488: Test failed: Regions are different

=== w1064 (64 bit msg) ===
msg.c:6482: Test failed: Update region shouldn't be empty
msg.c:6716: Test failed: InvalidateErase: 0: the msg sequence is not complete: expected 0085 - actual 0000
msg.c:6718: Test failed: Paint: 0: the msg sequence is not complete: expected 000f - actual 0000
msg.c:6488: Test failed: Regions are different
msg.c:6488: Test failed: Regions are different
msg.c:6488: Test failed: Regions are different
msg.c:7438: Test failed: destroy child on thread exit: 3: the msg sequence is not complete: expected 0000 - actual 001a