Determine Address Family (IPv4 or IPv6) in configuration file at runtime

[Sergey Popovich]

Having mostly identical configurations for IPv4 and IPv6 BIRD
(especially routing policies) with few AFI specific parts we try
to aggregate common part for both IPv4 and IPv6 in external
include file.

However there is need in some branch parts to known address family 
at configuration file processing by bird:
  for example to properly use maximum prefix length (IPv4: 32, IPv6: 128).

Is there are any way to known (some constant, etc.) in configuration
for which AFI bird was build?

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SP5474-RIPE
Sergey Popovich