The RPKI protocol (RFC 6810) using the RTRLib
(http://rpki.realmv6.org/) that is integrated inside
the BIRD's code.

Implemeted transports are:
 - unprotected transport over TCP
 - secure transport over SSHv2

Example configuration of bird.conf:
  ...
  roa4 table r4;
  roa6 table r6;

  protocol rpki {
    debug all;

    # Import both IPv4 and IPv6 ROAs
    roa4 { table r4; };
    roa6 { table r6; };

    # Set cache server (validator) address,
    # overwrite default port 323
    remote "rpki-validator.realmv6.org" port 8282;

    # Overwrite default time intervals
    retry   10;         # Default 600 seconds
    refresh 60;         # Default 3600 seconds
    expire 600;         # Default 7200 seconds
  }

  protocol rpki {
    debug all;

    # Import only IPv4 routes
    roa4 { table r4; };

    # Set cache server address to localhost,
    # use default ports tcp => 323 or ssh => 22
    remote 127.0.0.1;

    # Use SSH transport instead of unprotected transport over TCP
    ssh encryption {
      bird private key "/home/birdgeek/.ssh/id_rsa";
      remote public key "/home/birdgeek/.ssh/known_hosts";
      user "birdgeek";
    };
  }
  ...

To avoid byzantine behavior in case of some errors, linked lists are
cleared after rem_node() and resource headers are cleared after rfree().

I/O:
 - BSD: specify src addr on IP sockets by IP_HDRINCL
 - BSD: specify src addr on UDP sockets by IP_SENDSRCADDR
 - Linux: specify src addr on IP/UDP sockets by IP_PKTINFO
 - IPv6: specify src addr on IP/UDP sockets by IPV6_PKTINFO
 - Alternative SKF_BIND flag for binding to IP address
 - Allows IP/UDP sockets without tx_hook, on these
   sockets a packet is discarded when TX queue is full
 - Use consistently SOL_ for socket layer values.

OSPF:
 - Packet src addr is always explicitly set
 - Support for secondary addresses in BSD
 - Dynamic RX/TX buffers
 - Fixes some minor buffer overruns
 - Interface option 'tx length'
 - Names for vlink pseudoifaces (vlinkX)
 - Vlinks use separate socket for TX
 - Vlinks do not use fixed associated iface
 - Fixes TTL for direct unicast packets
 - Fixes DONTROUTE for OSPF sockets
 - Use ifa->ifname instead of ifa->iface->name

Now it compiles and mostly works.

This also fixes bug that timer->recurrent was not cleared
in tm_new() and unexpected recurrence of startup timer
in BGP confused state machine and caused crash.

Not quite standard construction, i should add
some autoconf macro.

Not tested yet.

Also does some reorganization in RT LSA announcement.

Filter code used 'aux' integer field of 'symbol' struct to store ptr
to next symbol and both 'aux2' and 'def' fields for value.
Changed to just 'def' for value and 'aux2' for ptr to next symbol.
Also another minor bugfix.

to see what resource does the address given as a parameter belong to.

and other non-portable functions on all systems.

over EFence and also hopefully smaller memory overhead, but sadly it's non-free
for commercial use).

If the DMALLOC_OPTIONS environment variable is not set, switch on `reasonable'
checks by default.

Also introduced mb_allocz() for cleared mb_alloc().

Complete resource manages and IP address handling.