outbound.c: destroy response to OPTIONS keepalive only when it is no more used
outbound.c: destroy response to OPTIONS keepalive only when it is no more used

darcs-hash:20080721170654-65a35-31178d318cb69d4076a6e93f74241e3ccac4a7f7.gz

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