[PATCH v5 1/2] user32/tests:Add test function Used to verify the child window Z order problem.【请注意，邮件由[e-mail]代发】

[Jiajin Cui]

I found that the z-order of window on WIN system will not change when HWND_TOPMOST and HWND_NOTOPMOST attributes are set for the same level window with WS_CHILD style, but it will change in wine, resulting in the problem of overlapping window, so I wrote a test function to explain this problem.

v2：
Add git log information
v3:
Move the path to fixup_flags function, only used to fix SetWindowPos function problem.
v4:
Divide a path into two pathes, better explain the prolem. and add notopmost verification
v5:
Add todo_wine to test patch[PATCH v5 1/2], and optimize fixup_flags[PATCH v5 2/2].

Signed-off-by: Jiajin Cui