Add enough Windows functionality to run WASI tutorial (#22)

* Add partial impl of determine_type_rights fn

* Add draft of fd_fdstat_get hostcall

* Add writev wrapper for writing IoVec in RawHandle

* Move IoVec and writev to separate helper crate

* Add Win error handling

Clean up closing and duplicating RawHandle

* Wrap Win file type result

* Add draft impl of fd_close and fd_read

* Refactor getting file access rights

* Remove winapi from the main Cargo.toml

* Add very rough draft of open_path (very incomplete)

* Clean up WinError with macro

* Ignore dir handle in openat if path absolute

* Decode oflags and advance open_path hostcall

* Clean up AccessRight and FlagsAndAttributes flags

* Implement path_get (without symlink expansion yet!)

* Add ShareMode and fix path_get for nested paths

* Add some error mappings between Win and WASI

* Clean up fdflags conversions

* Fix sharing violation when calling openat at '.'

* Apply Alex's fix of using ManuallyDrop instead forget

* Clean up

* Explicitly specify workspace to avoid comp errors at tests

winx/src/lib.rs

@@ -0,0 +1,33 @@
+#![deny(
+    // missing_docs,
+    trivial_numeric_casts,
+    unused_extern_crates,
+    unstable_features
+)]
+#![warn(unused_import_braces)]
+#![cfg_attr(feature = "clippy", plugin(clippy(conf_file = "../clippy.toml")))]
+#![cfg_attr(feature = "cargo-clippy", allow(clippy::new_without_default))]
+#![cfg_attr(
+    feature = "cargo-clippy",
+    warn(
+        clippy::float_arithmetic,
+        clippy::mut_mut,
+        clippy::nonminimal_bool,
+        clippy::option_map_unwrap_or,
+        clippy::option_map_unwrap_or_else,
+        clippy::unicode_not_nfc,
+        clippy::use_self
+    )
+)]
+
+#[macro_use]
+extern crate bitflags;
+
+pub mod file;
+pub mod handle;
+pub mod io;
+pub mod winerror;
+
+use winerror::WinError;
+
+pub type Result<T> = std::result::Result<T, WinError>;