Clean up system options code

Abort with error message when trying to use unsupported/disabled
system specific option.

conf.h

@@ -75,12 +75,7 @@ extern int CNF_AllowLocalReference(int *stratum);
 
 extern void CNF_SetupAccessRestrictions(void);
 
-#if defined(HAVE_SCHED_SETSCHEDULER)
-extern int SchedPriority;
-#endif
-
-#if defined(HAVE_MLOCKALL)
-extern int LockAll;
-#endif
+extern int CNF_GetSchedPriority(void);
+extern int CNF_GetLockMemory(void);
 
 #endif /* GOT_CONF_H */