message: AcceptBlock(), reject invalid PoS stake
diff: @@ -4655,6 +4655,11 @@ bool AcceptBlock(CBlock& block, CValidationState& state, CBlockIndex** ppindex,
  if(!stakeTxIn.IsZerocoinSpend()) {
  for (CTxIn in: stakeTxIn.vin) {
  const CCoins* coin = coins.AccessCoins(in.prevout.hash);
  +
  + if(!coin && !isBlockFromFork){
  + // No coins on the main chain
  + return error("%s: coin stake inputs not available on main chain", __func__);
  + }
  if(coin && !coin->IsAvailable(in.prevout.n)){
  // If this is not available get the height of the spent and validate it with the forked height
  // Check if this occurred before the chain split
  