user32/tests: Mark built-in wndproc auto-detection behaviour as broken on Windows 8 and 10.

[Huw Davies]

> On 23 Nov 2016, at 12:46, Dmitry Timoshkov <dmitry at baikal.ru> wrote:
> 
> Huw Davies <huw at codeweavers.com> wrote:
> 
>> +    SendMessageW(hwnd, WM_GETTEXT, sizeof(buf) / sizeof(buf[0]), (LPARAM)buf);
>> +    if (IsWindowUnicode(hwnd))
>> +        ok(memcmp(buf, unistring, sizeof(unistring)) == 0, "WM_GETTEXT invalid return\n");
>> +    else
>> +        ok(memcmp(buf, unistring, sizeof(unistring)) != 0, "WM_GETTEXT invalid return\n");
> 
> This doesn't look right. SendMessageW(WM_GETTEXT) is supposed to always
> return a unicode string regardless of wheather IsWindowUnicode() is broken
> or not, otherwise a lot of applications would misbehave in weird ways.
> This needs further investigation.

Exactly, the reason I added that bit was to show that this behaviour
is truly broken.

Huw.