Switch database mutex to recursive because we copy it everywhere

... and I have no idea if any of the calls are re-entrant. yay.

world/cli/cli_database_concurrency.cpp

@@ -76,7 +76,7 @@ void WorldserverCLI::TestDatabaseConcurrency(int argc, char **argv, argh::parser
 		return;
 	}
 
-	std::shared_ptr<std::mutex> sharedMutex = std::make_shared<std::mutex>();
+	std::shared_ptr<DBcore::Mutex> sharedMutex = std::make_shared<DBcore::Mutex>();
 
 	db.SetMutex(sharedMutex);