test_offer_answer.c: added test for media error while generating response to INVITE
test_offer_answer.c: added test for media error while generating response to INVITE

The status returned to the client is not updated if there is an internal
error while generating the response.

darcs-hash:20070412150751-65a35-5420e496a957f334c6a6347a14417eea12417aa5.gz

jart/sofia-sip,jart/sofia-sip,unispeech/sofia-sip,BelledonneCommunications/sofia-sip,BelledonneCommunications/sofia-sip,xhook/sofia-sip,xhook/sofia-sip,xhook/sofia-sip,erdincay/sofia-sip,xhook/sofia-sip,unispeech/sofia-sip,erdincay/sofia-sip,BelledonneCommunications/sofia-sip,BelledonneCommunications/sofia-sip,erdincay/sofia-sip,erdincay/sofia-sip,jart/sofia-sip,unispeech/sofia-sip,xhook/sofia-sip,unispeech/sofia-sip