xapian-bridge C port

endlessm/eos-sdk#2463
Is `$dc_install_base` a documented thing that we can rely on or an internal Automake thing? I didn't know about it and can't seem to find it in the docs. If this is reliable, then consider opening a backlog issue to change https://github.com/endlessm/eos-event-recorder-daemon/blob/master/Makefile.am#L23 as well :smile: