Enable Android build (#384)

* Support build for target_os android

The target_os `android` is quite similar to `linux` but must be
mentioned in the guards explicitly. Tested for target
`aarch64-linux-android`.

* Add target aarch64-linux-android to ci

Use `cross` for building target `aarch64-linux-android`. In the `ci`
workflow the matrix branch of `os` `ubuntu-latest` is used because the
matrix organization is host os centric instead of target.

Releases are build with `cross` for target `aarch64-linux-android`.

Install `cross` if needed for a run. At the time of writing the latest
release of `cross` can't build binaries for target
`aarch64-linux-android` and it's common sense that the latest git tag or
`master` shall be used [1].

[1] https://github.com/cross-rs/cross/issues/1222

* Add android related readme section

CHANGELOG.md

@@ -7,17 +7,22 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/)
 ## [Unreleased]
 
 ## Fixed
+
 * Remove redundant imports #377 - @cyqsimon
 * CI: use GitHub API to exempt dependabot from changelog requirement #378 - @cyqsimon
 * Remove unnecessary logging synchronisation #381 - @cyqsimon
 * Apply suggestions from new clippy lint clippy::assigning_clones #382 - @cyqsimon
 * Fix IPv6 socket detect logic #383 - @cyqsimon
+* Support build for `target_os`` `android` #384 - @flxo
 
 ## Added
+
 * CI: include generated assets in release archive #359 - @cyqsimon
 * Add PID column to the process table #379 - @notjedi
+* CI: add builds for target `aarch64-linux-android` #384 - @flxo
 
 ## Changed
+
 * CI: strip release binaries for all targets #358 - @cyqsimon
 * Bump MSRV to 1.74 (required by clap 4.5; see #373)
 * CI: Configure dependabot grouping #395 - @cyqsimon