glib/functions: fix get_charset logic

[lucab]

This tweaks get_charset() signature and logic to properly return
both the charset label and the UTF-8 boolean.

[lucab]

/cc @sdroege

[lucab]

(The header at the top of this file says it is auto-generated, but I didn't actually see where else the logic I'm patching would be coming from)

[sdroege]

There's a generator.py at the top-level :)

You'll have to edit the glib/Gir.toml to ignore this function (GLib.* is the "object" the contains all global functions) and then add a manual implementation to glib/src/functions.rs that basically does what you did here

[lucab]

@sdroege thanks for the pointers, I'll massage the PR in that direction.

[lucab]

Amended, it should be slightly less nasty now (and I've checked that generator.py is not angry about it) 😃

[lucab]

Amended to reshuffle the unsafe block. Thanks again for the prompt feedback and for maintaining this!

[sdroege]

Thanks for fixing this, looks good to me now :)