Resolver: improved code readability.
Resolver: improved code readability.

Renamed ngx_resolver_query_t to ngx_resolver_hdr_t as it describes
the header that is common to DNS queries and answers.

Replaced the magic number 12 by the size of the header structure.

The other changes are self-explanatory.

firebase/nginx,hy0kl/nginx,firebase/nginx,firebase/nginx,hy0kl/nginx,hy0kl/nginx,firebase/nginx