prevent Mix from creating DAG

mix/MixClient.cpp

@@ -42,6 +42,18 @@ namespace mix
 Secret const c_defaultUserAccountSecret = Secret("cb73d9408c4720e230387d956eb0f829d8a4dd2c1055f96257167e14e7169074");
 u256 const c_mixGenesisDifficulty = 131072; //TODO: make it lower for Mix somehow
 
+namespace
+{
+
+struct MixPow //dummy POW
+{
+	typedef int Solution;
+	static void assignResult(int, BlockInfo const&) {}
+	static bool verify(BlockInfo const&) { return true; }
+};
+
+}
+
 bytes MixBlockChain::createGenesisBlock(h256 _stateRoot)
 {
 	RLPStream block(3);
@@ -250,7 +262,7 @@ void MixClient::mine()
 {
 	WriteGuard l(x_state);
 	m_state.commitToMine(bc());
-	m_state.completeMine<Ethash>(Ethash::Solution());
+	m_state.completeMine<MixPow>(0);
 	bc().import(m_state.blockData(), m_state.db(), ImportRequirements::Default & ~ImportRequirements::ValidNonce);
 	m_state.sync(bc());
 	m_startState = m_state;