To help cross compilation, don't use glib-genmarshal in our
build. This is easy now that we have g_cclosure_marshal_generic().
In gobject/, add gmarshal.[ch] to git (making the existing entry
points stubs).
In gio/, simply switch to using g_cclosure_marshal_generic().
https://bugzilla.gnome.org/show_bug.cgi?id=652168
Makes explicit the fact that you are interacting with the individual
action rather than the group and removes potential namespace conflicts
with classes implementing the interface (like g_application_activate()
vs g_application_activate_action()).
Move all the annotations over from gobject-introspection.
They will not be used directly by the introspection scanner for now,
instead they will be extracted by a script and updated manually
until introspection is properly integrated into the glib build
