Misc (re #1751): do not update RTCP TX statistic if sending RTP in stream (audio and video) fails

git-svn-id: http://svn.pjsip.org/repos/pjproject@4816 74dad513-b988-da41-8d7b-12977e46ad98
Closed #1760: added pjsip_tcp_transport_get_socket() API to get the raw socket handle from SIP TCP transport

git-svn-id: http://svn.pjsip.org/repos/pjproject@4817 74dad513-b988-da41-8d7b-12977e46ad98