Fix compilation warnings.
Fix compilation warnings.

* test/test_context.c
  (test_serf_connection_request_create,
  test_serf_connection_priority_request_create,
  test_serf_closed_connection, test_serf_setup_proxy,
  test_keepalive_limit_one_by_one,
  test_keepalive_limit_one_by_one_and_burst): Make functions static.

jandre/serf,jandre/serf,jandre/serf,jandre/serf