xapian-bridge C port

endlessm/eos-sdk#2463
Unfortunately I still get the error:
```
/daemon/starts-successfully: OK
/daemon/get-empty-fails: OK
/daemon/get-returns-ok: **
ERROR:test/test-daemon.c:251:assert_db_exists: assertion failed (error == NULL): Could not connect: Connection refused (g-io-error-quark, 39)
```
I tested my hunch by adding `g_usleep(100000);` to the end of `setup()` and in that case it passes. I am running the tests on a VM so everything is probably slower than what you are developing on. I think what's missing is some way to know when the Soup server is ready to receive requests. However, I can also understand just sticking the 100ms wait in there...