Fix warnings on missing prototypes in test code

* test/mock_buckets.c
  (serf_mock_destroy): make static function
* test/test_server.c
  (test_listen_auth_http,test_listen_auth_http2): make
  static function


git-svn-id: https://svn.apache.org/repos/asf/serf/trunk@1718956 13f79535-47bb-0310-9956-ffa450edef68
2 files changed