Remove Android builds

The present build relies on the Android Native Development Kit (NDK)
which requires ongoing maintenance effort to provide integration
between GitHub Actions, the Ubuntu image (and associated NDK package)
it uses, local developer environments (eg Arch Linux in my case) etc.

This maintenance effort presently has no benefit given LmdbJava does
not support Android and it is unlikely to support Android in the near
future given long-standing open issues with JNR. As such the Android
native builds have been removed.

Author: bp-alex

README.md

@@ -15,7 +15,7 @@ Maven dependency resolution process.
 
 This project is intended to be executed by GitHub Actions, as Linux, Windows and
 macOS operating systems are all required. Linux is used for compiling the Linux
-and Android modules, whereas Windows and macOS compile their modules.
+modules, whereas Windows and macOS compile their modules.
 
 ### Versioning