context: always set GC callback
context: always set GC callback

Right now we only set the GC callback if gc-notifications are enabled.

This commit makes us always set the callback as prep work toward fixing a GC
deadlock.

https://bugzilla.gnome.org/show_bug.cgi?id=670200

endlessm/gjs,endlessm/gjs,mtwebster/cjs,pixunil/cjs,endlessm/gjs,djdeath/gjs,djdeath/gjs,pixunil/cjs,mtwebster/cjs,endlessm/gjs,pixunil/cjs,djdeath/gjs,mtwebster/cjs,pixunil/cjs,djdeath/gjs,mtwebster/cjs,pixunil/cjs,mtwebster/cjs,djdeath/gjs,endlessm/gjs