* tport_type_udp.c: use IP_MTU_DISCOVER socket option to turn off DF flag
  
  Added check for IP_MTU_DISCOVER in m4/sac-su2.m4



git-svn-id: http://svn.freeswitch.org/svn/freeswitch/trunk@8022 d0543943-73ff-0310-b7d9-9358b9ac24b2