Fix position carried in wxSpin{Button,Ctrl} events for 32 bit values in wxMSW.

Fix position carried in wxSpin{Button,Ctrl} events for 32 bit values in wxMSW.

Don't use WM_VSCROLL message parameter as the position because it's a 16 bit
value and is not enough for the spin controls using 32 bit range. Just use the
current value available from the control itself instead.

This fixes assert failures in the spin page of the widgets sample when
changing the value of a control when it is > SHRT_MAX.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@72410 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775