Dvoecot LUA support
Since Dovecot release 2.3.0 there is support for LUA-script-based passdbs and userdbs, however this support is currently not being build in alpine.
In order to enable LUA support just a few changes are necessary:
- add the lua dev package to makedepends
- add a lua subpackage
- add —with-lua=plugin to the _configure call in build()
- create the subpackage with the _lua
(from redmine: issue id 10215, created on 2019-04-08)