Only restrict input to wxMSW wxSpinCtrl to digits only if it doesn't support negative values, otherwise the user can't enter any negative numbers. As there is no built in support for entering digits and minus sign only, simply allow all characters to be used if the negative numbers must indeed be possible to enter. Closes #11082. git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@61754 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775