Add a compile command to Wasmtime.

This commit adds a `compile` command to the Wasmtime CLI.

The command can be used to Ahead-Of-Time (AOT) compile WebAssembly modules.

With the `all-arch` feature enabled, AOT compilation can be performed for
non-native architectures (i.e. cross-compilation).

The `Module::compile` method has been added to perform AOT compilation.

A few of the CLI flags relating to "on by default" Wasm features have been
changed to be "--disable-XYZ" flags.

A simple example of using the `wasmtime compile` command:

```text
$ wasmtime compile input.wasm
$ wasmtime input.cwasm
```

tests/all/module.rs

@@ -1,57 +1,61 @@
+use anyhow::Result;
+use std::io::BufWriter;
 use wasmtime::*;
 
 #[test]
 fn caches_across_engines() {
-    let mut c = Config::new();
-    c.cranelift_clear_cpu_flags();
+    let c = Config::new();
 
     let bytes = Module::new(&Engine::new(&c).unwrap(), "(module)")
         .unwrap()
         .serialize()
         .unwrap();
 
-    let res = Module::deserialize(
-        &Engine::new(&Config::new().cranelift_clear_cpu_flags()).unwrap(),
-        &bytes,
-    );
+    let res = Module::deserialize(&Engine::new(&Config::new()).unwrap(), &bytes);
     assert!(res.is_ok());
 
     // differ in shared cranelift flags
     let res = Module::deserialize(
-        &Engine::new(
-            &Config::new()
-                .cranelift_clear_cpu_flags()
-                .cranelift_nan_canonicalization(true),
-        )
-        .unwrap(),
+        &Engine::new(&Config::new().cranelift_nan_canonicalization(true)).unwrap(),
         &bytes,
     );
     assert!(res.is_err());
 
     // differ in cranelift settings
     let res = Module::deserialize(
-        &Engine::new(
-            &Config::new()
-                .cranelift_clear_cpu_flags()
-                .cranelift_opt_level(OptLevel::None),
-        )
-        .unwrap(),
+        &Engine::new(&Config::new().cranelift_opt_level(OptLevel::None)).unwrap(),
         &bytes,
     );
     assert!(res.is_err());
 
-    // differ in cpu-specific flags
+    // Missing required cpu flags
     if cfg!(target_arch = "x86_64") {
         let res = Module::deserialize(
-            &Engine::new(unsafe {
-                &Config::new()
-                    .cranelift_clear_cpu_flags()
-                    .cranelift_other_flag("has_sse3", "true")
-                    .unwrap()
-            })
-            .unwrap(),
+            &Engine::new(&Config::new().cranelift_clear_cpu_flags()).unwrap(),
             &bytes,
         );
         assert!(res.is_err());
     }
 }
+
+#[test]
+fn aot_compiles() -> Result<()> {
+    let engine = Engine::default();
+    let mut writer = BufWriter::new(Vec::new());
+    Module::compile(
+        &engine,
+        "(module (func (export \"f\") (param i32) (result i32) local.get 0))".as_bytes(),
+        &mut writer,
+    )?;
+
+    let bytes = writer.into_inner()?;
+    let module = Module::from_binary(&engine, &bytes)?;
+
+    let store = Store::new(&engine);
+    let instance = Instance::new(&store, &module, &[])?;
+
+    let f = instance.get_typed_func::<i32, i32>("f")?;
+    assert_eq!(f.call(101).unwrap(), 101);
+
+    Ok(())
+}