win32: Remove most special casing of WINPOSCHANGED during modal ops

win32: Remove most special casing of WINPOSCHANGED during modal ops

There is no particular reason to special case this, we want to handle all
sort of normal events. The only special thing we keep is that
as an optimization we pump the message loop extra during a WINPOSCHANGED
in a modal operation as that will cause us to repaint faster.

Also, bump the arbitrary number of mainloop iterations for the timer.
I don't see why we need it at all, but at least doing more than one
iteration if needed should be nice.