add a void *obj to contain any pointer.

If the answer to an upstream query is a CNAME which points to an
A/AAAA record which also exists in /etc/hosts and friends, then
caching is suppressed, to avoid inconsistent answers. This is
now modified to allow caching when the upstream and local A/AAAA
records have the same value.

This should solve problems people are seeing when a file changes
twice within a second and thus is missed for polling.

Make sure dst_addr is assigned the correct address in receive_query when OPTNOWILD is
enabled so the assigned mark can be correctly retrieved and set in forward_query when
conntrack is enabled.
Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>