This is the 2.x branch, not really supported or actively developed as of Dec 2017.
Support for 2.x is still possible by request but at the moment we have zero customers running 2.x builds :)
The more current 3.x branch is active but in stealth mode for now.
The binaries for 3.x are now available at http://sphinxsearch.com/downloads/current/
The sources for 3.x will also be posted here when we decide to make those available.