Auto merge of #1005 - bitcartel:zc.v0.11.2.z4_issue_857_optimize, r=ebfull
Auto merge of #1005 - bitcartel:zc.v0.11.2.z4_issue_857_optimize, r=ebfull

Equihash - Optimization to DistinctIndices function (rebased PR)

Update to DistinctIndices function (for issue #857).
Replaces pull request #974.

bitcoinsSG/zcash,aniemerg/zcash,CTRoundTable/Encrypted.Cash,aniemerg/zcash,aniemerg/zcash,bitcoinsSG/zcash,CTRoundTable/Encrypted.Cash,CTRoundTable/Encrypted.Cash,CTRoundTable/Encrypted.Cash,bitcoinsSG/zcash,bitcoinsSG/zcash,CTRoundTable/Encrypted.Cash,aniemerg/zcash,bitcoinsSG/zcash,bitcoinsSG/zcash,aniemerg/zcash,CTRoundTable/Encrypted.Cash,aniemerg/zcash