IPv6 support for SIP TCP and TLS transports and PJSUA-LIB v2

[bennylp]

This ticket implements the following.

IPv6 Support for SIP TCP and TLS Transports

Implement IPv6 for SIP TCP and TLS transports.

IPv6 Support in PJSUA-LIB v2

The PJSUA-LIB version 2 was lacking IPv6 support, especially in using the IPv6 media transports. This ticket adds new setting to the account config to enable IPv6 media on the account:

/** Specify how IPv6 transport should be used in account config. */
typedef enum pjsua_ipv6_use
{
    /** IPv6 is not used. */
    PJSUA_IPV6_DISABLED,

    /** IPv6 is enabled. */
    PJSUA_IPV6_ENABLED

} pjsua_ipv6_use;

struct pjsua_acc_config
{
    ...
    /** Specify whether IPv6 should be used on media. */
    pjsua_ipv6_use ipv6_media_use;
    ...
};

Application can enable IPv6 media by setting ipv6_media_use above. Note that this will only enable IPv6 in the media; for the signaling, application must instantiate IPv6 SIP transport separately. Hence indeed IPv6 media can be used with IPv4 signaling or vice versa.

Fix the Bound Address Bug in Outgoing TCP and TLS Transports

For TCP and TLS, there is a but that client (i.e. outgoing/connecting) sockets are not bound to the configured bound address. This fixes ticket #1575.

Notes

1. Please note that host resolution is still not supported for IPv6, hence IP addresses must be used throughout.
2. Our ICE implementation still doesn't support IPv6.
3. IPv6 support has not been tested on Symbian port.

[bennylp]

In 4262:

Fixed #1585: IPv6 support for SIP TCP and TLS transports and PJSUA-LIB v2