Merge #477

477: Add wasm32-wasi support for V3, V4, and V5 r=kinggoesgaming a=sunfishcode

**I'm submitting a(n)** feature

# Description

When the wasm32 architecture is used with WASI, md5, getrandom, and sha1
are all available, so V3, V4, and V5 can be enabled.

# Motivation

I'm porting an application that uses `uuid` to WASI and would like to add support.

# Tests

`cargo test --target=wasm32-wasi --all-features` passes.

Co-authored-by: Dan Gohman <sunfish@mozilla.com>
Co-authored-by: Hunar Roop Kahlon <kinggoesgaming@users.noreply.github.com>

README.md

@@ -46,7 +46,7 @@ various pieces of functionality:
   `serde` crate.
 
 You need to enable one of the following Cargo features together with
-`v3`, `v4` or `v5` feature if you're targeting `wasm32` architecture:
+`v3`, `v4` or `v5` feature if you're targeting `wasm32-unknown-unknown` target:
 
 * `stdweb` - enables support for `OsRng` on `wasm32-unknown-unknown` via
   `stdweb` combined with `cargo-web`

src/lib.rs

@@ -44,7 +44,8 @@
 //!   `serde` crate.
 //!
 //! You need to enable one of the following Cargo features together with
-//! `v3`, `v4` or `v5` feature if you're targeting `wasm32` architecture:
+//! `v3`, `v4` or `v5` feature if you're targeting `wasm32-unknown-unknown`
+//! target:
 //!
 //! * `stdweb` - enables support for `OsRng` on `wasm32-unknown-unknown` via
 //!   [`stdweb`] combined with [`cargo-web`]
@@ -160,6 +161,7 @@ mod test_util;
     feature = "v3",
     any(
         not(target_arch = "wasm32"),
+        target_os = "wasi",
         all(
             target_arch = "wasm32",
             any(feature = "stdweb", feature = "wasm-bindgen")
@@ -171,6 +173,7 @@ mod v3;
     feature = "v4",
     any(
         not(target_arch = "wasm32"),
+        target_os = "wasi",
         all(
             target_arch = "wasm32",
             any(feature = "stdweb", feature = "wasm-bindgen")
@@ -182,6 +185,7 @@ mod v4;
     feature = "v5",
     any(
         not(target_arch = "wasm32"),
+        target_os = "wasi",
         all(
             target_arch = "wasm32",
             any(feature = "stdweb", feature = "wasm-bindgen")