[PATCH v2] user32:Fix z order error when child window want to be topmost windows

when set_window_pos the second param is HWND_TOPMOST,
window with WS_CHILD do not change z order.

Signed-off-by: cuijiajin <cuijiajin(a)uniontech.com>
---
 dlls/user32/tests/win.c | 88 +++++++++++++++++++++++++++++++++++++++++
 dlls/user32/winpos.c    |  6 +++
 2 files changed, 94 insertions(+)