Support Istanbul in aleth-vm tool (#5762)

Support Istanbul in aleth-vm tool

CHANGELOG.md

@@ -24,6 +24,7 @@
 - Added: [#5751](https://github.com/ethereum/aleth/pull/5751) Istanbul support: EIP-152 Add BLAKE2 compression function `F` precompile.
 - Added: [#5755](https://github.com/ethereum/aleth/pull/5755) testeth now runs `stChainId`, `stSLoadTest`, `stSelfBalance` tests for Istanbul.
 - Added: [#5758](https://github.com/ethereum/aleth/pull/5758) Istanbul support: activation in Ropsten config.
+- Added: [#5762](https://github.com/ethereum/aleth/pull/5762) aleth-vm supports `--network Istanbul` option.
 - Changed: [#5532](https://github.com/ethereum/aleth/pull/5532) The leveldb is upgraded to 1.22. This is breaking change on Windows and the old databases are not compatible.
 - Changed: [#5559](https://github.com/ethereum/aleth/pull/5559) Update peer validation error messages.
 - Changed: [#5568](https://github.com/ethereum/aleth/pull/5568) Improve rlpx handshake log messages and create new rlpx log channel.

aleth-vm/main.cpp

@@ -114,7 +114,7 @@ int main(int argc, char** argv)
 
     po::options_description networkOptions("Network options", c_lineWidth);
     networkOptions.add_options()("network", po::value<string>(),
-        "Main|Ropsten|Homestead|Frontier|Byzantium|Constantinople|ConstantinopleFix\n");
+        "Main|Ropsten|Homestead|Frontier|Byzantium|Constantinople|ConstantinopleFix|Istanbul\n");
 
     po::options_description optionsForTrace("Options for trace", c_lineWidth);
     auto addTraceOption = optionsForTrace.add_options();
@@ -212,9 +212,11 @@ int main(int argc, char** argv)
     if (vm.count("network"))
     {
         string network = vm["network"].as<string>();
-        if (network == "ConstantinopleFix")
+        if (network == "Istanbul")
+            networkName = Network::IstanbulTest;
+        else if (network == "ConstantinopleFix")
             networkName = Network::ConstantinopleFixTest;
-        if (network == "Constantinople")
+        else if (network == "Constantinople")
             networkName = Network::ConstantinopleTest;
         else if (network == "Byzantium")
             networkName = Network::ByzantiumTest;