Add the GLIB_AVAILABLE_IN_ALL annotation to all old functions (that
haven't already been annotated with the GLIB_AVAILABLE_IN_* macros or a
deprecation macro).
If we discover in the future that we cannot use only one macro on
Windows, it will be an easy sed patch to fix that.
https://bugzilla.gnome.org/show_bug.cgi?id=688681
This is needed for thread-safety ... yes, it would have been better to
make get_object() return a full reference and have something like a
peek_object() method return a borrowed reference for C convenience
(only a single vfunc would have been needed). But such an ABI break is
too late now...
Signed-off-by: David Zeuthen <davidz@redhat.com>