On Windows 7 and older versions of Windows, calling GetCurrentObject(hdc, OBJ_BITMAP) for a display
device context will return a valid handle. However, this handle will fail for GetObject(). On newer
versions of Windows, GetCurrentObject(hdc, OBJ_BITMAP) for display device contexts returns a bitmap
of virtual screen size and its size changes after display mode changes. This behavior is tested in
the _check_display_dc() function in user32/tests/monitor.c.

The screen shot function of WeChat depends on GetObject() to either return failure or a valid size
for the bitmap from display device contexts. Since Wine currently report Windows 7 as default and to
save memory, the Windows 7 behavior is implemented.
Signed-off-by: Zhiyi Zhang <zzhang@codeweavers.com>