Update utils.h

The NRPE agent and the check_nrpe plugin by default, would log errors to syslog.
Added the ability to turn off logging to syslog and set the default to be off.

include/utils.h

@@ -49,5 +49,6 @@ void open_log_file();
 void logit(int priority, const char *format, ...);
 void close_log_file();
 void display_license(void);
+extern int enable_syslog;
 
 #endif