[reSIProcate] rutil/dns/DnsAAAARecord dependency on resip/stack/config.hxx

[Robert Sparks]

main currently has this odd dependency.

Building DnsAAAARecord down inside rutil requires resip/stack to have
build built enough for config.hxx to exist (assuming the non-autotools 
build system).

  We have a design goal to have librutil build by itself - what's this 
dependency about
and can we remove it quickly?

RjS