xapian-bridge C port

endlessm/eos-sdk#2463
I'm getting an assertion failure on this line when I run the tests with no xapian-bridge process already running. I'm not sure why, but perhaps the process from the previous test isn't getting cleaned up fast enough or perhaps the test is starting before the process is ready to receive requests.

```
/daemon/starts-successfully: OK
/daemon/get-empty-fails: OK
/daemon/get-returns-ok: **
ERROR:test/test-daemon.c:241:assert_db_exists: assertion failed (error == NULL): Could not connect: Connection refused (g-io-error-quark, 39)
```