Supress struct/class mismatch warnings introduced in #10284.

Author: paveljanik

src/wallet/wallet.h

@@ -77,7 +77,7 @@ class CScheduler;
 class CTxMemPool;
 class CBlockPolicyEstimator;
 class CWalletTx;
-class FeeCalculation;
+struct FeeCalculation;
 
 /** (client) version numbers for particular wallet features */
 enum WalletFeature