Removed unused == operator from CMutableTransaction.

Author: lucash-dev

src/primitives/transaction.h

@@ -388,11 +388,6 @@ struct CMutableTransaction
      */
     uint256 GetHash() const;
 
-    friend bool operator==(const CMutableTransaction& a, const CMutableTransaction& b)
-    {
-        return a.GetHash() == b.GetHash();
-    }
-
     bool HasWitness() const
     {
         for (size_t i = 0; i < vin.size(); i++) {