Fix use of "options" broken by recent merging

config.h

@@ -17,6 +17,9 @@
  *
  */
 
+#ifndef _CONFIG_H_
+#define _CONFIG_H_
+
 #include "repmgr.h"
 
 typedef struct {
@@ -31,3 +34,5 @@ typedef struct {
 void parse_config(const char* config_file, t_configuration_options* options);
 void parse_line(char *buff, char *name, char *value);
 char *trim(char *s);
+
+#endif