refactor: encapsulate flags get access for all other checks

No behavior change. This prepares moving the cache entry
flags field to private access.

src/coins.h

@@ -131,6 +131,7 @@ struct CCoinsCacheEntry
     explicit CCoinsCacheEntry(Coin&& coin_) : coin(std::move(coin_)), flags(0) {}
     CCoinsCacheEntry(Coin&& coin_, unsigned char flag) : coin(std::move(coin_)), flags(flag) {}
 
+    inline unsigned char GetFlags() const noexcept { return flags; }
     inline bool IsDirty() const noexcept { return flags & DIRTY; }
     inline bool IsFresh() const noexcept { return flags & FRESH; }
 };

src/test/coins_tests.cpp

@@ -603,7 +603,7 @@ void GetCoinsMapEntry(const CCoinsMap& map, CAmount& value, char& flags, const C
         } else {
             value = it->second.coin.out.nValue;
         }
-        flags = it->second.flags;
+        flags = it->second.GetFlags();
         assert(flags != NO_ENTRY);
     }
 }