sipp

When running sipp in IPv6 environment two errors was discovered.

1) If you run 2 sipp instances on the PC with 2 network interfaces it was
not possible to start each instance on different IP address but same port.
With different ports it worked. To assign local IP address to sipp the
command line parameter -i was used. In IPv4 environment the same
configuration worked fine.

The cause is that for IPv6 the command line parameter is ignored and sipp
binds all local IP addresses.

2) Pcap play functionality did not work properly. It was not possible to
send RTP packets on IPv6 address specified in SDP.

The cause is that in function get_remote_ipv6_media() the parameter addr
is passed by value not by reference. Therefore any changes done in this
function are not propagated to the caller.

This patch addresses both bugs:
1) In the sipp.cpp module is the function open_connections() is removed
condition for IPv6 address family on line 5203. I added also memset on the
4938 from security reason.

2) In the call.cpp module in the function get_remote_ipv6_media() the
parameter struct in6_addr addr was changed to struct in6_addr *addr. Also
all calls of the function and usage of addr parameter inside
get_remote_ipv6_media() were changed.