Concurrent Balance modification in ConsolidateRewards when all rewards consolidated

[kuegi]

ConsolidateRewards expects the List to contain each address only once. If it occurs multiple times, the same address might be consolidated multiple times "at once" (on different threads) which can lead to rewards being added multiple times in error.

The method doesn't even need a List of owner:balance as input but should rather receive a set which in itself already guarantees the uniqueness.

This is most likely also the reason for the chain split a few weeks ago where a MN used consolidaterewards and had an address get the rewards added multiple times.

ain/src/init.cpp

Lines 2207 to 2215 in cd46ef7

	LogPrintf("Consolidate rewards for all addresses..\n");
	std::vector<std::pair<CScript, CAmount>> balancesToMigrate;
	pcustomcsview->ForEachBalance([&](CScript const& owner, CTokenAmount balance) {
	if (balance.nValue > 0) {
	balancesToMigrate.emplace_back(owner, balance.nValue);
	}
	return true;
	});
	ConsolidateRewards(*pcustomcsview, ::ChainActive().Height(), balancesToMigrate, true);