Github Actions do not allow to overwrite already stored cache for
specific key. This caching approach is suitable for projects, where
dependencies are being tracked within lock files or their alternatives,
for exapmle NPM, Ruby or Python. Termux-packages is not such repository
where we can easily retrieve cache by using old key and generate a new
one after building was finished.
* Weight-based mirror selection: do not give each mirror same usage ratio as hosts have different properties.
* Rotate mirrors after 6h: pkg now checks usability of all mirrors before selecting one, this takes time but we may want to reduce delays before the actual `apt` operation will be started.
* Update apt cache after 20min: reduce amount of necessary package list queries. We even can go with 1h, but since we prefer origin repository over mirrors as download source, 20 minutes should be fine.
* Avoid long lines.
* Add missing info for some commands.
* Do not show deb cache size if its size cannot be determined, for example if cache dir was deleted.
The openssl code is unmaintained [1] and I get errors about
certificate verification failure on one of my emails ("TLS certificate
verification failed: the certificate owner does not match
hostname"). With gnutls everything works.
[1] https://marlam.de/msmtp/news/openssl-discouraged
See https://github.com/termux/termux-packages/issues/5620.
Implements automatic mirror selection:
* Pick a random URL of top 4 mirrors of Termux main repository and use it during 30 minutes limit, then rotate to a new one. Distribute traffic accross multiple mirrors, including origin Bintray repository.
* During 30 minutes limit, let `pkg` to check whether mirror is accessible on each run. If mirror is not accessible, use a new one. Mirrors are not guaranteed to be 100% accessible, so let pkg to check which one is working before using `apt`.
* Skip rotating if using `.cn` mirrors - Chinese users will not want to use something else due to great firewall and download speed issues.
