codegen: Add abi-stability path for classes
codegen: Add abi-stability path for classes

https://bugzilla.gnome.org/show_bug.cgi?id=789069

frida/vala,GNOME/vala,GNOME/vala,frida/vala,GNOME/vala,frida/vala,GNOME/vala,frida/vala,frida/vala