Add new GLib 0.14 variant types for metadata types

This way it's more convenient for downstream crates like ostree-rs-ext
to convert loaded variants.

TODO: Can we add a feature for the `gvariant` crate and expose via
that too?

rust-bindings/rust/src/core.rs

@@ -0,0 +1,21 @@
+//! Hand written bindings for ostree-core.h
+
+use glib::VariantDict;
+
+/// The type of a commit object: `(a{sv}aya(say)sstayay)`
+pub type CommitVariantType = (
+    VariantDict,
+    Vec<u8>,
+    Vec<(String, Vec<u8>)>,
+    String,
+    String,
+    u64,
+    Vec<u8>,
+    Vec<u8>,
+);
+
+/// The type of a dirtree object: `(a(say)a(sayay))`
+pub type TreeVariantType = (Vec<(String, Vec<u8>)>, Vec<(String, Vec<u8>, Vec<u8>)>);
+
+/// The type of a directory metadata object: `(uuua(ayay))`
+pub type DirmetaVariantType = (u32, u32, u32, Vec<(Vec<u8>, Vec<u8>)>);

rust-bindings/rust/src/lib.rs

@@ -27,6 +27,9 @@ pub use crate::auto::*;
 // handwritten code
 mod checksum;
 pub use crate::checksum::*;
+mod core;
+pub use crate::core::*;
+
 #[cfg(any(feature = "v2018_6", feature = "dox"))]
 mod collection_ref;
 #[cfg(any(feature = "v2018_6", feature = "dox"))]