Revert "Remove adding callback_guard"

[EPashkin]

This reverts commit a61ccc1.

Part of gtk-rs/glib#250

cc @GuillaumeGomez, @sdroege

[EPashkin]

Or better add config for this?

[GuillaumeGomez]

A default cfg! maybe?

[EPashkin]

@GuillaumeGomez Sorry, I don't understand.

[GuillaumeGomez]

I meant we added a new feature (in Cargo.toml) and it was a default one so it can be disabled. Better? :)

[EPashkin]

This way gir with from same commit can produce different result.
Not sure that it good idea.
Hm. I wrong, you can't change features in Cargo.toml without adding new commit (ignoring --no-default-features flag).
I don't see difference without this and just adding commit.
I meant adding option to Gir.toml.

[EPashkin]

.. but as "my" option in "Gir.toml" will be used only year or half maybe it unnecessary work.

[GuillaumeGomez]

I suppose... Let's just revert everything and avoid any unnecessary work.

[sdroege]

Yes, revert simply and then we revert the reverts in 1-2 months again.