fix for ipv4 early return/search

[bluejekyll]

If ndots is greater than for, then this skips the early return of the IP address, and delays that until the final result after performing all other queries.

fixes: #431

[bluejekyll]

@briansmith, you filed this original issue. Let me know if you see any issues with this patch to resolve it.

I still need to add a testcase for this logic, so it's not ready to merge yet.

[codecov]

Codecov Report

Merging #467 into master will increase coverage by 0.05%.
The diff coverage is 97.29%.

@@            Coverage Diff             @@
##           master     #467      +/-   ##
==========================================
+ Coverage   86.51%   86.57%   +0.05%     
==========================================
  Files         133      133              
  Lines       13429    13496      +67     
==========================================
+ Hits        11618    11684      +66     
- Misses       1811     1812       +1

Impacted Files	Coverage Δ
resolver/src/lookup_ip.rs	90.22% <83.33%> (-0.1%)	⬇️
resolver/src/resolver_future.rs	76.92% <98.52%> (+3.88%)	⬆️
proto/src/tcp/tcp_client_stream.rs	92.4% <0%> (-1.27%)	⬇️
proto/src/rr/domain/label.rs	92.47% <0%> (+0.44%)	⬆️

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