Remove dead code related to invalid joinsplit sigs

src/main.cpp

@@ -1340,22 +1340,6 @@ bool ContextualCheckTransaction(int32_t slowflag,const CBlock *block, CBlockInde
 
     }
 
-    if (!(tx.IsMint() || tx.vjoinsplit.empty()))
-    {
-        BOOST_STATIC_ASSERT(crypto_sign_PUBLICKEYBYTES == 32);
-
-        // We rely on libsodium to check that the signature is canonical.
-        // https://github.com/jedisct1/libsodium/commit/62911edb7ff2275cccd74bf1c8aefcc4d76924e0
-        if (crypto_sign_verify_detached(&tx.joinSplitSig[0],
-                                        dataToBeSigned.begin(), 32,
-                                        tx.joinSplitPubKey.begin()
-                                        ) != 0) {
-            return state.DoS(isInitBlockDownload() ? 0 : 100,
-                                error("CheckTransaction(): invalid joinsplit signature"),
-                                REJECT_INVALID, "bad-txns-invalid-joinsplit-signature");
-        }
-    }
-
     if (tx.IsCoinBase())
     {
         if (!ContextualCheckCoinbaseTransaction(slowflag,block,previndex,tx, nHeight,validateprices))