-extern const std::string engine_info(bool to_uci = false);
-extern int cpu_count();
-extern void timed_wait(WaitCondition&, Lock&, int);
-extern void prefetch(char* addr);
-extern void start_logger(bool b);
+const std::string engine_info(bool to_uci = false);
+void timed_wait(WaitCondition&, Lock&, int);
+void prefetch(char* addr);
+void start_logger(bool b);