atk/atkversion.h.in: Add Version/Deprecation Macros
This adds version macros, like what is now done in GLib, GTK+ and Clutter,
so that these macros can be used in public headers to:
-Prepare for using a visibility-based (or __declspec(dllexport)method to
export the public APIs during the build. These macros are marked for 2.x
stable releases as ATK_AVAILABLE_IN_X_Y, and ATK_AVAILABLE_IN_ALL for APIs
introduced on or before the ATK-2.0.0 release.
-Add ATK_DEPRECATED_IN_X_Y macros for use on APIs that are deprecated
in 2.x, and ATK_DEPRECATED for those deprecated earlier. This
is also used to export the deprecated APIs using the visibility-based/
__declspec(dllexport) method.
https://bugzilla.gnome.org/show_bug.cgi?id=728031