message: fix(vfs) Make `host_fs` the default file system.
diff: @@ -14,6 +14,7 @@ typetag = { version = "0.1", optional = true }
  serde = { version = "1.0", default-features = false, features = ["derive"], optional = true }
  [features]
  +default = ["host_fs"]
  host_fs = ["libc"]
  mem_fs = []
  enable-serde = [
  