message: wallet, refactor: Immutable CWalletTx::pwallet
diff: @@ -263,7 +263,7 @@ int CalculateMaximumSignedInputSize(const CTxOut& txout, const CWallet* pwallet,
  class CWalletTx
  {
  private:
  - const CWallet* pwallet;
  + const CWallet* const pwallet;
  /** Constant used in hashBlock to indicate tx has been abandoned, only used at
  * serialization/deserialization to avoid ambiguity with conflicted.
  