Don't allow wxSpinCtrl range to include negative values if base != 10 (wxMSW)

In a native up-down control hexadecimal numbers are always unsigned (see
UDM_SETBASE message documentation) so we need to prevent:
- Setting a range including negative values if base == 16.
- Setting base != 10 if current range includes negative values.

See #18805.

include/wx/private/spinctrl.h

@@ -26,6 +26,8 @@ extern int GetMaxValueLength(int minVal, int maxVal, int base);
 // of wxSpinCtrl is derived from wxSpinButton but uses the same algorithm.
 extern wxSize GetBestSize(const wxControl* spin, int minVal, int maxVal, int base);
 
+// Helper function to check if given combination of range and base is valid.
+extern bool IsBaseCompatibleWithRange(int minVal, int maxVal, int base);
 } // namespace wxSpinCtrlImpl
 
 #endif // _WX_PRIVATE_SPINCTRL_H_