db/Configured: migrate from class Error to C++ exceptions

src/db/DatabaseGlue.hxx

@@ -26,15 +26,16 @@ struct ConfigBlock;
 class EventLoop;
 class DatabaseListener;
 class Database;
-class Error;
 
 /**
  * Initialize the database library.
  *
+ * Throws #std::runtime_error on error.
+ *
  * @param block the database configuration block
  */
 Database *
 DatabaseGlobalInit(EventLoop &loop, DatabaseListener &listener,
-		   const ConfigBlock &block, Error &error);
+		   const ConfigBlock &block);
 
 #endif