* Added arm64 Linux standalone build. (No autobuilder yet.)
* Improved termux installation process.
Added git-annex-install.sh script to avoid user needing to type as much in
termux. The scope of this script is limited; runshell handles the rest.
Runshell runs termux-fix-shebang on the shell scripts. The problem is
the bundled bin/sh script, deleting that script also works, but then the
others probably use the system Android /bin/sh, which could be old or
broken or not posix or whatever. Using termux sh to run the scripts is
better.
This commit was sponsored by Eric Drechsel on Patreon.