Codeset information is sent only in the first request in the service_context
field of GIOP request message. However, CORBA::Object::_validate_connection()
uses LocateRequest message and this kind of message doesn't have
service_context field. If validate_connection is the first remote call in the
application the transport is marked as the one that already sent the first
request and thus no codeset negotiation happens in subsequent call. So, the
solution for this problem is to restore TAO_Transport::first_request_ flag to
it's state before LocateRequest message was sent. We check the later in this
test.

_Expected successful result_:

$ ./run_test.pl
(9909|140389579343600) server - event loop finished

_Expected regression result_:

$ ./run_test.pl
Test FAILED after LocateRequest (bug#3676 is not fixed)!!
(9931|67366400) server - event loop finished