sres: fix poll error in sres_blocking.c

Thanks to <yuri AT rawbw DOT com> for catching this.
nta: add function nta_leg_get_call_id() to <sofia-sip/nta.h>
nua: fix crash in case of response timeout
nua: do not bind BYE to session dialog usage

Problem reported by Jerry Richards.
check_nua: fix timing issue in bye_4_2_2
check_session: test case for 200-OK-after-BYE-sent problem
test_nua: disable test_bye_after_receiving_401_to_update()

Stack is now trying harder to send the BYE.
nua: use NUTAG_DEFERRABLE_TIMERS()
Update RELEASE
su: fix su_time() on 64-bit OS X

The field tv_sec in struct timeval is 64bits instead of 32bits as in
su_time_t, so you cannot cast su_time_t to struct timeval.
tport: do not check MSG_TRUNC behaviour anymore
Fix crash in function nua_session_client_response