libstd: add xous to libstd

Add the `xous` target to libstd. Currently this defers everything to the
`unsupported` target.

Signed-off-by: Sean Cross <sean@xobs.io>

library/std/build.rs

@@ -37,6 +37,7 @@ fn main() {
         || target.contains("nintendo-3ds")
         || target.contains("vita")
         || target.contains("nto")
+        || target.contains("xous")
         // See src/bootstrap/synthetic_targets.rs
         || env::var("RUSTC_BOOTSTRAP_SYNTHETIC_TARGET").is_ok()
     {

library/std/src/sys/mod.rs

@@ -44,6 +44,9 @@ cfg_if::cfg_if! {
     } else if #[cfg(target_family = "wasm")] {
         mod wasm;
         pub use self::wasm::*;
+    } else if #[cfg(target_os = "xous")] {
+        mod xous;
+        pub use self::xous::*;
     } else if #[cfg(all(target_vendor = "fortanix", target_env = "sgx"))] {
         mod sgx;
         pub use self::sgx::*;

library/std/src/sys/xous/mod.rs

@@ -0,0 +1,44 @@
+#![deny(unsafe_op_in_unsafe_fn)]
+
+#[path = "../unsupported/alloc.rs"]
+pub mod alloc;
+#[path = "../unsupported/args.rs"]
+pub mod args;
+#[path = "../unix/cmath.rs"]
+pub mod cmath;
+#[path = "../unsupported/env.rs"]
+pub mod env;
+#[path = "../unsupported/fs.rs"]
+pub mod fs;
+#[path = "../unsupported/io.rs"]
+pub mod io;
+#[path = "../unsupported/locks/mod.rs"]
+pub mod locks;
+#[path = "../unsupported/net.rs"]
+pub mod net;
+#[path = "../unsupported/once.rs"]
+pub mod once;
+#[path = "../unsupported/os.rs"]
+pub mod os;
+#[path = "../unix/os_str.rs"]
+pub mod os_str;
+#[path = "../unix/path.rs"]
+pub mod path;
+#[path = "../unsupported/pipe.rs"]
+pub mod pipe;
+#[path = "../unsupported/process.rs"]
+pub mod process;
+#[path = "../unsupported/stdio.rs"]
+pub mod stdio;
+#[path = "../unsupported/thread.rs"]
+pub mod thread;
+#[path = "../unsupported/thread_local_key.rs"]
+pub mod thread_local_key;
+#[path = "../unsupported/thread_parking.rs"]
+pub mod thread_parking;
+#[path = "../unsupported/time.rs"]
+pub mod time;
+
+#[path = "../unsupported/common.rs"]
+mod common;
+pub use common::*;

library/std/src/sys_common/mod.rs

@@ -46,6 +46,7 @@ cfg_if::cfg_if! {
     if #[cfg(any(target_os = "l4re",
                  feature = "restricted-std",
                  all(target_family = "wasm", not(target_os = "emscripten")),
+                 target_os = "xous",
                  all(target_vendor = "fortanix", target_env = "sgx")))] {
         pub use crate::sys::net;
     } else {