Switch to libsecp256k1-based validation for ECDSA

src/bitcoin-tx.cpp

@@ -445,9 +445,15 @@ static void MutateTxSign(CMutableTransaction& tx, const string& flagStr)
 
 class Secp256k1Init
 {
+    ECCVerifyHandle globalVerifyHandle;
+
 public:
-    Secp256k1Init() { ECC_Start(); }
-    ~Secp256k1Init() { ECC_Stop(); }
+    Secp256k1Init() {
+        ECC_Start();
+    }
+    ~Secp256k1Init() {
+        ECC_Stop();
+    }
 };
 
 static void MutateTx(CMutableTransaction& tx, const string& command,