Add option to ignore initstepslew and makestep directives

When chronyd is started with -R, the initstepslew directive and the
makestep directive with a positive limit will be ignored. This is useful
when restarting chronyd to avoid unnecessary clock adjustments. It can
be used with -r.

conf.h

@@ -29,6 +29,8 @@
 
 #include "addressing.h"
 
+extern void CNF_SetRestarted(int);
+
 extern char *CNF_GetRtcDevice(void);
 
 extern void CNF_ReadFile(const char *filename);