Fix the loop unrolling inside resolve_ads().

Fix the loop unrolling inside resolve_ads().

If we don't get an IP list don't use interpret_string_addr(), as this only returns one address, use interpret_string_addr_internal() instead.

The last 4 patches address bug #8910 (resolve_ads() code can return zero
addresses and miss valid DC IP addresses).
(cherry picked from commit b9d3f8258396873d6ec8b6ea9ad066e2f1f8e973)