Vendor dependencies

Let's see how I like this workflow.

vendor/io-lifetimes/Cargo.toml

@@ -0,0 +1,94 @@
+# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
+#
+# When uploading crates to the registry Cargo will automatically
+# "normalize" Cargo.toml files for maximal compatibility
+# with all versions of Cargo and also rewrite `path` dependencies
+# to registry (e.g., crates.io) dependencies.
+#
+# If you are reading this file be aware that the original Cargo.toml
+# will likely look very different (and much more reasonable).
+# See Cargo.toml.orig for the original contents.
+
+[package]
+edition = "2018"
+name = "io-lifetimes"
+version = "1.0.3"
+authors = ["Dan Gohman <dev@sunfishcode.online>"]
+include = [
+    "src",
+    "build.rs",
+    "Cargo.toml",
+    "COPYRIGHT",
+    "LICENSE*",
+    "/*.md",
+]
+description = "A low-level I/O ownership and borrowing library"
+readme = "README.md"
+keywords = [
+    "api",
+    "io",
+]
+categories = [
+    "os",
+    "rust-patterns",
+]
+license = "Apache-2.0 WITH LLVM-exception OR Apache-2.0 OR MIT"
+repository = "https://github.com/sunfishcode/io-lifetimes"
+
+[dependencies.fs-err]
+version = "2.6.0"
+optional = true
+
+[features]
+close = [
+    "libc",
+    "windows-sys",
+]
+default = ["close"]
+
+[target."cfg(not(target_os = \"wasi\"))".dependencies.async-std]
+version = "1.12.0"
+optional = true
+
+[target."cfg(not(target_os = \"wasi\"))".dependencies.mio]
+version = "0.8.0"
+features = [
+    "net",
+    "os-ext",
+]
+optional = true
+
+[target."cfg(not(target_os = \"wasi\"))".dependencies.os_pipe]
+version = "1.0.0"
+features = ["io_safety"]
+optional = true
+
+[target."cfg(not(target_os = \"wasi\"))".dependencies.socket2]
+version = "0.4.0"
+optional = true
+
+[target."cfg(not(target_os = \"wasi\"))".dependencies.tokio]
+version = "1.6.0"
+features = [
+    "io-std",
+    "fs",
+    "net",
+    "process",
+]
+optional = true
+
+[target."cfg(not(windows))".dependencies.libc]
+version = "0.2.96"
+optional = true
+
+[target."cfg(windows)".dependencies.windows-sys]
+version = "0.42.0"
+features = [
+    "Win32_Foundation",
+    "Win32_Storage_FileSystem",
+    "Win32_Networking_WinSock",
+    "Win32_Security",
+    "Win32_System_IO",
+    "Win32_System_Threading",
+]
+optional = true