[http_service_test] Add http_service_tests.cmx

This allows http_service_tests to link the shared libraries in
the package.

Test: run_test fuchsia-pkg://fuchsia.com/http_service_tests#meta/http_service_tests.cmx
Test: check http_service_tests is successful in the CQ log

CONN-7 #done

Change-Id: I81a8efe6f0ce546604185030f28612aa9bec7d9d
3 files changed