Vendor dependencies

Let's see how I like this workflow.

vendor/errno/Cargo.toml

@@ -0,0 +1,35 @@
+# 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]
+name = "errno"
+version = "0.2.8"
+authors = ["Chris Wong <lambda.fairy@gmail.com>"]
+description = "Cross-platform interface to the `errno` variable."
+documentation = "https://docs.rs/errno"
+categories = ["os"]
+license = "MIT/Apache-2.0"
+repository = "https://github.com/lambda-fairy/rust-errno"
+
+[features]
+default = ["std"]
+std = []
+[target."cfg(target_os=\"dragonfly\")".dependencies.errno-dragonfly]
+version = "0.1.1"
+[target."cfg(target_os=\"hermit\")".dependencies.libc]
+version = "0.2"
+[target."cfg(target_os=\"wasi\")".dependencies.libc]
+version = "0.2"
+[target."cfg(unix)".dependencies.libc]
+version = "0.2"
+[target."cfg(windows)".dependencies.winapi]
+version = "0.3"
+features = ["errhandlingapi", "minwindef", "ntdef", "winbase"]