Update status bar fields widths from WM_SIZE handler.

Update status bar fields widths from WM_SIZE handler.

Doing it immediately after calling ::SetWindowPos(), as we used to do, didn't
work correctly (presumably because the status bar fields widths were not
updated yet internally) and resulted in not updating the ellipsized fields
values when "Show window contents while dragging" Windows option was off.
Doing it when we get WM_SIZE works in this case too.

Closes #13257.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67884 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775