message: fix(wasi) Re-organize the Cargo features.
  The following changes are applied by this patch:
  * `default` enables `sys-default`,
  * `sys-default` enables `sys`, which enables `wasmer/sys` (this part
  was missing! `wasmer` never had its `sys` feature enabled),
  * `js-default` enables `js`.
  The rest doesn't change.
diff: @@ -17,47 +17,43 @@ crate-type = ["cdylib", "rlib"]
  cfg-if = "1.0"
  thiserror = "1"
  generational-arena = { version = "0.2", features = ["serde"] }
  -tracing = { version = "0.1" }
  -getrandom = { version = "0.2" }
  -typetag = { version = "0.1", optional = true }
  -serde = { version = "1.0", default-features = false, features = ["derive"], optional = true }
  +tracing = "0.1"
  +getrandom = "0.2"
  wasmer-wasi-types = { path = "../wasi-types", version = "2.0.0" }
  wasmer = { path = "../api", version = "2.0.0", default-features = false }
  wasmer-vfs = { path = "../vfs", version = "2.0.0", default-features = false }
  +typetag = { version = "0.1", optional = true }
  +serde = { version = "1.0", default-features = false, features = ["derive"], optional = true }
  +
  +[target.'cfg(unix)'.dependencies]
  +libc = { version = "^0.2", default-features = false }
  [target.'cfg(windows)'.dependencies]
  winapi = "0.3"
  -[target.'cfg(unix)'.dependencies]
  -libc = { version = "^0.2", default-features = false }
  +[target.'cfg(target_arch = "wasm32")'.dependencies]
  +wasm-bindgen = "0.2.74"
  +
  +[target.'cfg(target_arch = "wasm32")'.dev-dependencies]
  +wasm-bindgen-test = "0.3.0"
  +tracing-wasm = "0.2"
  [features]
  -default = ["logging", "host_fs"]
  -enable-serde = [
  - "typetag",
  - "serde",
  -]
  +default = ["sys-default"]
  +
  +sys = ["wasmer/sys"]
  +sys-default = ["sys", "logging", "host_fs"]
  +
  +js = ["wasmer/js", "mem_fs", "getrandom/js"]
  +js-default = ["js"]
  +test-js = ["js", "wasmer/js-default", "wasmer/wat"]
  +
  +host_fs = ["wasmer-vfs/host_fs"]
  +mem_fs = ["wasmer-vfs/mem_fs"]
  +
  logging = ["tracing/log"]
  disable-all-logging = [
  "tracing/release_max_level_off",
  "tracing/max_level_off"
  ]
  -host_fs = ["wasmer-vfs/host_fs"]
  -mem_fs = ["wasmer-vfs/mem_fs"]
  -js = [
  - "getrandom/js",
  - "mem_fs",
  - "wasmer/js",
  -]
  -test-js = [
  - "js",
  - "wasmer/js-default",
  - "wasmer/wat"
  -]
  -
  -[target.'cfg(target_arch = "wasm32")'.dependencies]
  -wasm-bindgen = "0.2"
  -
  -[target.'cfg(target_arch = "wasm32")'.dev-dependencies]
  -wasm-bindgen-test = "0.3.0"
  -tracing-wasm = { version = "0.2" }
  +enable-serde = ["typetag", "serde"]
  