Add block "confirmations" to getblock, mainly for identifying orphans

src/bitcoinrpc.cpp

@@ -172,6 +172,9 @@ Object blockToJSON(const CBlock& block, const CBlockIndex* blockindex)
 {
     Object result;
     result.push_back(Pair("hash", block.GetHash().GetHex()));
+    CMerkleTx txGen(block.vtx[0]);
+    txGen.SetMerkleBranch(&block);
+    result.push_back(Pair("confirmations", (int)txGen.GetDepthInMainChain()));
     result.push_back(Pair("size", (int)::GetSerializeSize(block, SER_NETWORK, PROTOCOL_VERSION)));
     result.push_back(Pair("height", blockindex->nHeight));
     result.push_back(Pair("version", block.nVersion));