ppsi.h: define DEFAULT_TIME_OPS and DEFAULT_NET_OPS as extern

This patch is need to make ppsi compile with a time- implementation
different than unix.

Signed-off-by: Aurelio Colosimo <aurelio@aureliocolosimo.it>

include/ppsi/ppsi.h

@@ -141,6 +141,9 @@ struct pp_network_operations {
 		    TimeInternal *t, int chtype, int use_pdelay_addr);
 };
 
+/* This is the struct pp_network_operations to be provided by time- dir */
+extern struct pp_network_operations DEFAULT_NET_OPS;
+
 /* These can be liked and used as fallback by a different timing engine */
 extern struct pp_network_operations unix_net_ops;
 
@@ -162,6 +165,9 @@ struct pp_time_operations {
 	unsigned long (*calc_timeout)(struct pp_instance *ppi, int millisec);
 };
 
+/* This is the struct pp_time_operations to be provided by time- dir */
+extern struct pp_time_operations DEFAULT_TIME_OPS;
+
 /* These can be liked and used as fallback by a different timing engine */
 extern struct pp_time_operations unix_time_ops;