Linux error numbers for Rust

This library defines an Error struct that represents error numbers returned from Linux system calls.

On Linux, error numbers are architecture-specific. The arch modules provide access to error numbers for all supported architectures, and the top-level module re-exports error numbers for the current target platform.

To depend on linux-errno from a Bazel workspace:

```python load("@bazeltools//tools/builddefs/repo:http.bzl", "http_archive")

httparchive( name = "rustposixerrno", sha256 = "0c86c849ff673372fe6415d4004a233565b57b2884ea49d3b725dd1296cc2529", stripprefix = "posix-errno-1.0.1", urls = ["https://github.com/jmillikin/rust-posix-errno/releases/download/v1.0.1/posix-errno-1.0.1.tar.xz"], )

httparchive( name = "rustlinuxerrno", # Obtain the package checksum from the release page: # https://github.com/jmillikin/rust-linux-errno/releases/tag/v1.0.1 sha256 = "", stripprefix = "linux-errno-1.0.1", urls = ["https://github.com/jmillikin/rust-linux-errno/releases/download/v1.0.1/linux-errno-1.0.1.tar.xz"], ) ```

To depend on linux-errno from a Cargo workspace:

[dependencies] linux-errno = { version = "1.0.1" }