Vendor dependencies

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vendor/errno/README.md

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+# errno [![CI](https://github.com/lambda-fairy/rust-errno/actions/workflows/main.yml/badge.svg)](https://github.com/lambda-fairy/rust-errno/actions/workflows/main.yml) [![Cargo](https://img.shields.io/crates/v/errno.svg)](https://crates.io/crates/errno)
+
+Cross-platform interface to the [`errno`][errno] variable. Works on Rust 1.13 or newer.
+
+Documentation is available at <https://docs.rs/errno>.
+
+[errno]: https://en.wikipedia.org/wiki/Errno.h
+
+
+## Dependency
+
+Add to your `Cargo.toml`:
+
+```toml
+[dependencies]
+errno = "*"
+libc = "*"
+```
+
+
+## Examples
+
+```rust
+extern crate errno;
+use errno::{Errno, errno, set_errno};
+
+// Get the current value of errno
+let e = errno();
+
+// Set the current value of errno
+set_errno(e);
+
+// Extract the error code as an i32
+let code = e.0;
+
+// Display a human-friendly error message
+println!("Error {}: {}", code, e);
+```