Initial reorg.

This is largely the same as #305, but updated for the current tree.

crates/wasi-common/wasi-common-cbindgen/tests/ref_args.rs

@@ -0,0 +1,20 @@
+extern crate wasi_common_cbindgen;
+
+pub use wasi_common_cbindgen::wasi_common_cbindgen;
+
+#[wasi_common_cbindgen]
+fn ref_args(a: &usize) -> usize {
+    a + 1
+}
+
+fn main() {
+    let a = Box::new(2);
+    let expected = ref_args(a.as_ref());
+    let given = unsafe {
+        let raw = Box::into_raw(a);
+        let res = wasi_common_ref_args(raw);
+        Box::from_raw(raw);
+        res
+    };
+    assert_eq!(given, expected);
+}