#89 Definition of constants not OS/architecture/device type dependent

[Henk-Jan van Tuyl]

There is no mechanism to handle definitions that depend on OS/architecture/device type,
as done with macros like __SMARTPHONE__ in wxWidget´s defs.h. See for
instance the definition of wxDEFAULT_CONTROL_BORDER in defs.h:

/* This makes it easier to specify a 'normal' border for a control */
#if defined(__SMARTPHONE__) || defined(__POCKETPC__)
#define wxDEFAULT_CONTROL_BORDER    wxBORDER_SIMPLE
#else
#define wxDEFAULT_CONTROL_BORDER    wxBORDER_SUNKEN
#endif