Support for multi-value wasm (#399)

* deps: bump wasmparser to 0.39.2

This has a bug fix for multi-value Wasm validation that is required for getting
the spec tests passing.

https://github.com/yurydelendik/wasmparser.rs/pull/135

* Update cranelift to 0.46.1 to get multi-value Wasm support

The `cranelift_wasm` APIs had to change a little bit to maintain state necessary
when translating multi-value Wasm blocks. The `translate_module` function now
returns a `ModuleTranslationState` that is borrowed during each function's
translation.

* Enable multi-value proposal's spec tests

This enables all the Wasm multi-value proposal's spec tests other than the ones
that rely on functions having more return values than registers available on the
target. That is not supported by cranelift yet.

* wasmtime-interface-types: always use multi-value Wasm

And remove the return pointer hacks that work around the lack of multi-value.

misc/wasmtime-py/Cargo.toml

@@ -12,11 +12,11 @@ name = "_wasmtime"
 crate-type = ["cdylib"]
 
 [dependencies]
-cranelift-codegen = "0.44.0"
-cranelift-native = "0.44.0"
-cranelift-entity = "0.44.0"
-cranelift-wasm = "0.44.0"
-cranelift-frontend = "0.44.0"
+cranelift-codegen = "0.46.1"
+cranelift-native = "0.46.1"
+cranelift-entity = "0.46.1"
+cranelift-wasm = "0.46.1"
+cranelift-frontend = "0.46.1"
 wasmtime-environ = { path = "../../wasmtime-environ" }
 wasmtime-interface-types = { path = "../../wasmtime-interface-types" }
 wasmtime-jit = { path = "../../wasmtime-jit" }
@@ -24,7 +24,7 @@ wasmtime-runtime = { path = "../../wasmtime-runtime" }
 target-lexicon = { version = "0.8.1", default-features = false }
 failure = "0.1"
 region = "2.0.0"
-wasmparser = "0.39.1"
+wasmparser = "0.39.2"
 
 [dependencies.pyo3]
 version = "0.8.0"