nua_session.c: auto-alert with 180 after PRACK, not with 183.
nua_session.c: auto-alert with 180 after PRACK, not with 183.

The INVITE transaction looped with 183 response if auto-alert was turned on
and 100rel was used.

darcs-hash:20070212154442-65a35-3618f02abfe4f0d287d2aaa31faf973a0205221c.gz

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