txdb: Increase max dbcache size to 1 TB

Author: luke-jr

src/txdb.h

@@ -24,7 +24,7 @@ class uint256;
 //! -dbcache default (MiB)
 static const int64_t nDefaultDbCache = 300;
 //! max. -dbcache (MiB)
-static const int64_t nMaxDbCache = sizeof(void*) > 4 ? 16384 : 1024;
+static constexpr int64_t nMaxDbCache = sizeof(void*) > 4 ? 1048576 : 1024;
 //! min. -dbcache (MiB)
 static const int64_t nMinDbCache = 4;
 //! Max memory allocated to block tree DB specific cache, if no -txindex (MiB)