Numerical statistics are truncated to 32-bits on export

Summary

In BIND statistics, values larger than 4294967295 overflow during export. E.g. any server which processes more 4294967295 queries will see nonsense in statistics. This can conceivably happen in practice within a single day if server is handling sustained ~ 50 k QPS.

Internally tracking still works up to 2^63-1, i.e. 9223372036854775807, but there is no way to get the data out without using debugger.

BIND version used

Broken by 4e5edb35, MR !1493 (merged).

Affects v9.19: f8fece81bf651275c3914d2559717943228a4cfd
Affects v9.18: acf55e12
Affects v9.16: 161d69ab

Steps to reproduce

It's kinda lengthy. Just do 2^32 queries and check /json/v1/server opcodes[] stats to see if they ever exceed 2^32-1.

What is the current bug behavior?

Counters are not monotonic because of the overflow during export.

What is the expected correct behavior?

No information loss.

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