[cairo] gobject boxed types

[Johan Dahlin]

Luiz Americo Pereira Camara wrote:
> Colin Walters wrote:
[..]
> Currently i use cairo in windows without dependency to glib or gtk. From
> what you said it will be possible to build cairo without glib dependency
> but the build that comes with gtk will be linked to glib.
> 
> The problem is that my users and i download cairo from gtk
> (http://www.gtk.org/download-windows.html), so i would have to build
> cairo myself  or find a glib free cairo binary elsewhere.

This can be avoided by loading glib in runtime instead of compile time.
If glib is found, load it and register the types.

People will now quickly point out that an installed glib doesn't necessarily
mean that the application uses it. Personally I think it's not a big deal, 
but it is possible to workaround that by checking if a glib specific symbol 
such as g_type_init is available in the main executable, eg if the 
executable was linked against glib and only then register the types.

That should make everybody happy.

Johan