Consensus: Minimal way to move dust out of consensus

Summary:
Backport of Core PR9278
https://github.com/bitcoin/bitcoin/pull/9279

Test Plan:

make check
test_runner.py

Reviewers: deadalnix, jasonbcox, Fabien, markblundeberg, O1 Bitcoin ABC, #bitcoin_abc

Reviewed By: Fabien, O1 Bitcoin ABC, #bitcoin_abc

Differential Revision: https://reviews.bitcoinabc.org/D3039